EP3740309A1

EP3740309A1 - Process for preparation of a specific catalyst for selective hydrogenation and hydrogenation of aromatic compounds by kneading

Info

Publication number: EP3740309A1
Application number: EP19700010.2A
Authority: EP
Inventors: Malika Boualleg; Anne-Claire Dubreuil
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2018-01-15
Filing date: 2019-01-02
Publication date: 2020-11-25
Anticipated expiration: 2039-01-02
Also published as: FR3076747B1; WO2019137836A1; US20200338531A1; EP3740309B1; FR3076747A1

Abstract

A process for the preparation of a catalyst comprising an oxide matrix and an active phase comprising nickel, which process comprises the following steps: - a calcined porous aluminium oxide is prepared; - the calcined porous aluminium oxide obtained is kneaded with a solution resulting from mixing one or more solution(s) comprising at least one nickel precursor and at least one solution comprising at least one organic compound which comprises at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amine function, or at least one amide function, in order to obtain a paste, wherein the mole ratio of said organic compound to the nickel element is between 0.01 and 5.0 mol/mol; - the paste obtained is shaped; - the shaped paste obtained is dried at a temperature of less than 250°C in order to obtain a dried catalyst.

Description

PROCESS FOR THE PREPARATION OF A PARTICULAR CATALYST OF SELECTIVE HYDROGENATION AND HYDROGENATION OF AROMATICS BY MIXING

Technical area

The subject of the invention is a process for the particular preparation of a catalyst used in the selective hydrogenation of polyunsaturated compounds in a hydrocarbon feedstock, especially in C2-C5 steam cracking cuts and steam cracking gasolines, or in the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feed allowing the conversion of aromatic compounds of petroleum or petrochemical cuts by conversion of aromatic rings to naphthenic rings.

State of the art

The most active catalysts in hydrogenation reactions are conventionally based on noble metals such as palladium or platinum. These catalysts are used industrially in refining and in petrochemistry for the purification of certain petroleum fractions by hydrogenation, in particular in reactions of selective hydrogenation of polyunsaturated molecules such as diolefins, acetylenics or alkenylaromates, or in hydrogenation reactions. aromatic. It is often proposed to substitute palladium for nickel, a less active metal than palladium. It is therefore necessary to dispose of it in greater quantity in the catalyst. Thus, the nickel-based catalysts generally have a metal content of between 5 and 60% by weight of nickel relative to the total weight of the catalyst.

The speed of the hydrogenation reaction is governed by several criteria, such as the diffusion of the reagents on the surface of the catalyst (external diffusional limitations), the diffusion of the reagents in the porosity of the support towards the active sites (internal diffusion limitations) and the intrinsic properties of the active phase such as the size of the metal particles and the distribution of the active phase within the support.

With regard to the internal diffusion limitations, it is important that the porous distribution of the macropores and mesopores is adapted to the desired reaction in order to ensure the diffusion of the reagents in the porosity of the support towards the active sites as well as the diffusion of the formed products. outwards.

SUBSTITUTE SHEET (RULE 26) As regards the size of the metal particles, it is generally accepted that the catalyst is all the more active as the size of the metal particles is small. In addition, it is important to obtain a particle size distribution centered on the optimum value and a narrow distribution around this value.

The often important content of nickel in the hydrogenation catalysts requires particular synthetic routes.

The most conventional way of preparing these catalysts is the impregnation of the support with an aqueous solution of a nickel precursor, followed generally by drying and calcination. Before their use in hydrogenation reactions these catalysts are generally reduced in order to obtain the active phase which is in metallic form (that is to say in the zero valency state). The nickel-based catalysts on alumina prepared by a single impregnation step generally make it possible to attain nickel contents of between 12 and 15% by weight of nickel, depending on the pore volume of the alumina used. When it is desired to prepare catalysts having a higher nickel content, several successive impregnations are often necessary to obtain the desired nickel content, followed by at least one drying step, then possibly a calcination step between each impregnation. .

Thus, the document WO201 1/080515 describes a catalyst based on nickel on alumina which is active in hydrogenation, especially aromatics, said catalyst having a nickel content greater than 35% by weight relative to the total weight of the catalyst, and a large nickel dispersion. metal on the surface of an alumina with a very open porosity and a high specific surface area. The catalyst is prepared by at least four successive impregnations. The preparation of nickel catalysts having a high nickel content by the impregnation route thus involves a sequence of numerous steps which increases the associated manufacturing costs.

Another route of preparation also used to obtain catalysts with a high nickel content is coprecipitation. The coprecipitation generally consists of a simultaneous casting in a batch reactor of both an aluminum salt (aluminum nitrate for example) and a nickel salt (nickel nitrate for example). Both salts precipitate simultaneously. Then calcination at high temperature is necessary to make the transition from alumina gel (boehmite for example) to alumina. By this preparation route, contents up to 70% by weight nickel are reached. Catalysts Prepared by coprecipitation are for example described in US 4,273,680, US 8,518,851 and US 2010/01 16717.

Finally, it is also known the preparation route by comalaxing. Comalaxing generally consists of a mixture of a nickel salt with an alumina gel such as boehmite, said mixture being subsequently shaped, generally by extrusion, then dried and calcined. US 5,478,791 discloses a nickel-on-alumina catalyst having a nickel content of between 10 and 60% by weight and a nickel particle size of 15 to 60 nm, prepared by comalling a nickel compound. with an alumina gel, followed by shaping, drying and reduction.

Moreover, in order to obtain better catalytic performances, in particular a better selectivity and / or activity, it is known in the state of the art to proceed with the use of organic compound additives for the preparation of catalysts. metal selective hydrogenation or hydrogenation of aromatics.

For example, the application FR2984761 discloses a process for the preparation of a selective hydrogenation catalyst comprising a support and an active phase comprising a group VIII metal, said catalyst being prepared by a process comprising a step of impregnating a solution containing a Group VIII metal precursor and an organic additive, more particularly an organic compound having one to three carboxylic acid functions, a step of drying the impregnated support, and a step of calcining the dried support to obtain the catalyst.

Document US2006 / 0149097 discloses a process for the hydrogenation of aromatic compounds of benzenepolycarboxylic acid type in the presence of a catalyst comprising an active phase comprising at least one Group VIII metal, which catalyst is prepared by a process comprising an impregnation step of a solution containing a group VIII metal precursor and a step of impregnating an organic additive of amine or amino acid type. The impregnation step of the organic additive may be carried out before or after the step of impregnating the active phase, or even simultaneously.

The Applicant has surprisingly discovered that a catalyst based on nickel supported on alumina, prepared by comalaxing a calcined aluminous porous oxide with a solution comprising at least one nickel precursor and at least one additive of organic compounds type chosen from organic compounds comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function or at least one amine function, makes it possible to obtain performances in selective hydrogenation of polyunsaturated compounds or in hydrogenation of aromatic compounds in at least as good or better than the known methods of the state of the art.

The resulting porous distribution of such a process of preparation by comalaxing makes it possible to provide a porosity particularly adapted to promote the diffusion of the reagents in the porous medium and then their reaction with the active phase. Indeed, in addition to reducing the number of steps and therefore the manufacturing cost, the advantage of a comparison compared to an impregnation is that significantly reduces any risk of partial blockage of the porosity of the support when the deposition of the active phase and thus the appearance of internal diffusion limitations.

In addition, such a catalyst used in the context of a process for the selective hydrogenation of polyunsaturated compounds or a process for the hydrogenation of aromatic or polyaromatic compounds has the particularity of being able to contain high amounts of active phase. Indeed, the fact of preparing the catalyst according to the invention by comalaxing makes it possible to strongly charge this catalyst in the active phase in a single pass.

It is important to emphasize that the catalyst obtained by the preparation method according to the invention is structurally distinguished from a catalyst obtained by simply impregnating a metal precursor on the alumina support in which the alumina forms the support and the active phase is introduced into the pores of this support. Without wishing to be bound by any theory, it appears that the preparation process according to the invention makes it possible to obtain a composite in which the nickel particles and the alumina are intimately mixed thus forming the structure of the catalyst with a porosity and an active phase content adapted to the desired reactions.

Objects of the invention

The present invention firstly relates to a process for preparing a catalyst comprising an oxide matrix having a calcined alumina content greater than or equal to 90% by weight relative to the total weight of said matrix, and an active phase comprising nickel, said active phase not comprising a group VIB metal, the nickel content being between 1 and 65% by weight of said element relative to the total weight of the catalyst, said active phase being in the form of nickel particles having a diameter less than or equal to 18 nm, said catalyst comprising a total pore volume measured by mercury porosimetry greater than 0.10 ml / g, a mesoporous volume measured by mercury porosimetry greater than 0.10 ml / g, a measured macroporous volume by mercury porosimetry less than or equal to 0.6 ml / g, a median mesoporous diameter of between 3 and 25 nm, a macroporous median diameter of between 50 and 1500 nm, and a SBET specific surface area of between 20 and 400 m ² / g, which method comprises the following steps:

a) a calcined aluminous porous oxide is prepared;

b) the aluminized calcined porous oxide obtained in step a) is kneaded with a solution resulting from a mixture of one or more solution (s) comprising at least one nickel precursor and at least one solution comprising at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amine function, or at least one amide function to obtain a paste, the molar ratio between said organic compound and the nickel element being between 0.01 and 5.0 mol / mol;

c) shaping the paste obtained in step b);

d) the shaped dough obtained in step c) is dried at a temperature below 250 ° C to obtain a dried catalyst;

e) optionally, a heat treatment of the dried catalyst obtained in step d) is carried out at a temperature of between 250 and 1000 ° C, in the presence or absence of water.

In one embodiment of the invention, said organic compound comprises at least one carboxylic acid function.

Preferably, said organic compound is chosen from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids and tetracarboxylic acids.

In one embodiment of the invention, said organic compound comprises at least one alcohol function.

Preferably, said organic compound is chosen from:

organic compounds comprising a single alcohol function;

organic compounds comprising two alcohol functions; organic compounds chosen from diethylene glycol, triethylene glycol, tetraethylene glycol, or a polyethylene glycol having the formula H (OC ₂ H ₄ ) _n OH with n greater than 4 and having an average molecular weight of less than 20000 g / mol; monosaccharides of formula C _n (H ₂ 0) _p with n between 3 and 12;

disaccharides, trisaccharides, or monosaccharide derivatives.

In one embodiment of the invention, said organic compound comprises at least one ester function.

Preferably, said organic compound is chosen from:

linear or cyclic or cyclic unsaturated esters of carboxylic acid;

organic compounds comprising at least two carboxylic acid ester functions;

organic compounds comprising at least one carboxylic acid ester function and at least one second functional group chosen from alcohols, ethers, ketones and aldehydes;

cyclic or linear esters of carbonic acid;

linear diesters of carbonic acid.

In one embodiment of the invention, said organic compound comprises at least one amide function.

Preferably, said organic compound is chosen from:

acyclic amides comprising one or two amide functions;

cyclic amides or lactams;

organic compounds comprising at least one amide function and a carboxylic acid function or an alcohol function;

organic compounds comprising at least one amide function and an additional nitrogen heteroatom.

In one embodiment according to the invention, said organic compound comprises at least one amine function corresponding to the empirical formula C _x N _y H _z in which x is between 1 and 20, y = 1-x and z = 2- (2x + 2).

In one embodiment according to the invention, which aluminized porous oxide calcined according to step a) is obtained by the following steps:

a1) a first step of precipitation, in an aqueous reaction medium, of at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide, and of at least one acidic precursor chosen from aluminum sulphate, aluminum chloride and nitrate of aluminum, sulfuric acid, hydrochloric acid and nitric acid, in which at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the aluminum-containing acidic and basic precursor (s) is adjusted so as to obtain a degree of progression of the first stage of between 5 and 13%, the degree of progress being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said first precipitation step relative to the total amount of alumina formed at the end of step a3) of the process preparation, said step operating at a temperature between 20 and 90 ° C and for a period of between 2 minutes and 30 minutes;

a2) a step of heating the suspension at a temperature between 40 and 90 ° C for a period of between 7 minutes and 45 minutes,

a3) a second step of precipitating the suspension obtained at the end of the heating step a2) by adding to the suspension at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, acid hydrochloric acid and nitric acid, wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10, And the flow rate of the aluminum-containing acidic and basic precursor (s) is adjusted so as to obtain a progress rate of the second step of between 87 and 95%, the rate of progress being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said second precipitation step relative to the total amount of alumina formed at the end of step a3) of the preparation process, said step operating at a temperature between 40 and 90 ° C and for a period of time between 2 minutes and 50 minutes;

a4) a filtration step of the suspension obtained at the end of the second precipitation step a3) to obtain an alumina gel;

a5) a step of drying said alumina gel obtained in step a4) to obtain a powder; a6) a step of heat treatment of the powder obtained at the end of step a5) between 500 and 1000 ° C, for a duration of between 2 and 10 h, in the presence or absence of a flow of air containing up to 60% water volume to obtain a calcined aluminous porous oxide. In one embodiment according to the invention, said calcined aluminous porous oxide according to step a) is obtained by the following steps: a1 ') a step of dissolving an aluminum acid precursor chosen from aluminum sulphate, aluminum chloride and aluminum nitrate in water, at a temperature of between 20 and 90 ° C, at a pH of between 0.5 and 5, for a period of between 2 and 60 minutes,

a2 ') a step of adjusting the pH by adding to the suspension obtained in step a1') at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide, at a temperature between 20 and 90 ° C, and at a pH between 7 and 10, for a period of between 5 and 30 minutes,

a3 ') a step of coprecipitation of the suspension obtained at the end of step a2') by adding to the suspension at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid and nitric acid, at least one of the basic or acidic precursors comprising aluminum, the relative flow rate of the acidic and basic precursors being chosen so as to obtain a pH of the reaction medium of between 7 and 10 and the flow rate of the aluminum-containing acidic and basic precursors being adjusted so as to obtain a final alumina concentration in the suspension of between 10 and 38 g / l,

a4 ') a filtration step of the suspension obtained at the end of the coprecipitation step a3') to obtain an alumina gel,

a5 ') a step of drying said alumina gel obtained in step a4') to obtain a powder, a6 ') a step of heat treatment of the powder obtained at the end of step a5') at a temperature between 500 and 1000 ° C, in the presence or absence of a flow of air containing up to 60% by volume of water, for a period of between 2 and 10 hours, to obtain a calcined aluminous porous oxide.

In one embodiment according to the invention, said calcined aluminous porous oxide according to step a) is obtained by the following steps:

a1 ") at least a first step of precipitating alumina, in aqueous reaction medium, of at least one basic precursor chosen from sodium aluminate, potassium aluminate, aqueous ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, in which at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen in such a way as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain a degree of progress. of said first step of between 40 and 100%, the advancement rate being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said first precipitation step relative to the total amount of alumina formed at the result of step c) of the preparation process, said first precipitation step operating at a temperature between 10 and 50 ° C, and for a period of between 2 minutes and 30 minutes;

a2 ") a heat treatment step of the suspension heated to a temperature between 50 and 200 ° C for a period of between 30 minutes and 5 hours to obtain an alumina gel;

a3 ") a filtration step of the suspension obtained at the end of step a2") of heat treatment, followed by at least one washing step of the gel obtained;

a4 ") a step of drying the alumina gel obtained at the end of step a3") to obtain a powder;

a5 ") a step of heat treatment of the powder obtained at the end of step a4") at a temperature of between 500 and 1000 ° C., with or without a flow of air containing up to 60 % by volume of water, to obtain a calcined aluminous porous oxide.

Another subject of the invention relates to a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as diolefins and / or acetylenics and / or alkenylaromates, contained in a hydrocarbon feedstock having a final boiling point less than or equal to 300 ° C., which process is carried out at a temperature of between 0 and 300 ° C., at a pressure of between 0.1 and 10 MPa, at a molar ratio of hydrogen / (polyunsaturated compounds) to be hydrogenated) between 0.1 and 10 and at a hourly space velocity of between 0.1 and 200 h ¹ when the process is carried out in the liquid phase, or at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) of between 0 and , 5 and 1000 and at an hourly volume rate between 100 and 40000 h ¹ when the process is carried out in the gas phase, in the presence of a catalyst obtained by the preparation process according to the invention.

Another object according to the invention relates to a process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point of less than or equal to 650 ° C., said process being carried out in phase gaseous or in liquid phase, at a temperature of between 30 and 350 ° C, at a pressure of between 0.1 and 20 MPa, at a molar ratio of hydrogen / (aromatic compounds with hydrogenate) between 0.1 and 10 and at a hourly volume velocity VVH between 0.05 and 50 h ¹ , in the presence of a catalyst obtained by the preparation process according to the invention.

Detailed description of the invention

Definitions

"Macropores" means pores whose opening is greater than 50 nm.

By "mesopores" is meant pores whose opening is between 2 nm and 50 nm, limits included.

By "micropores" is meant pores whose opening is less than 2 nm.

By total pore volume of the catalyst or the support used for the preparation of the catalyst according to the invention is meant the volume measured by mercury porosimeter intrusion according to the ASTM D4284-83 standard at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140 °. The anchoring angle was taken equal to 140 ° according to the recommendations of the book "Techniques of the engineer, treated analysis and characterization", pages 1050-1055, written by Jean Charpin and Bernard Rasneur.

In order to obtain a better accuracy, the value of the total pore volume corresponds to the value of the total pore volume measured by mercury porosimeter intrusion measured on the sample minus the value of the total pore volume measured by mercury porosimeter intrusion measured on the same sample for a pressure corresponding to 30 psi (about 0.2 MPa).

The volume of macropores and mesopores is measured by mercury intrusion porosimetry according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140 °. The value at which mercury fills all the intergranular voids is fixed at 0.2 MPa, and it is considered that beyond this mercury enters the pores of the sample.

The macroporous volume of the catalyst or support used for the preparation of the catalyst according to the invention is defined as the cumulative volume of mercury introduced at a pressure of between 0.2 MPa and 30 MPa, corresponding to the volume contained in the pores of diameter apparent greater than 50 nm. The mesoporous volume of the catalyst or support used for the preparation of the catalyst according to the invention is defined as the cumulative volume of mercury introduced at a pressure of between 30 MPa and 400 MPa, corresponding to the volume contained in the pores of apparent diameter included between 2 and 50 nm.

The micropore volume is measured by nitrogen porosimetry. The quantitative analysis of the microporosity is carried out using the "t" method (Lippens-De Boer method, 1965) which corresponds to a transformation of the starting adsorption isotherm as described in the book "Adsorption by powders and porous solids. Principles, methodology and applications "written by F. Rouquérol, J. Rouquérol and K. Sing, Academie Press, 1999.

The mesoporous median diameter is also defined as being the diameter such that all the pores, among all the pores constituting the mesoporous volume, of size less than this diameter constitute 50% of the total mesoporous volume determined by intrusion into the mercury porosimeter.

The macroporous median diameter is also defined as the diameter such that all the pores, among all the pores constituting the macroporous volume, of size less than this diameter constitute 50% of the total macroporous volume determined by intrusion into the mercury porosimeter.

By the specific surface of the catalyst or of the support used for the preparation of the catalyst according to the invention, the specific surface B.E.T. determined by nitrogen adsorption according to ASTM D 3663-78 established from the BRUNAUER-EMMETT-TELLER method described in the journal "The Journal of the American Society", 60, 309, (1938).

The size of the nickel nanoparticles is understood to mean the average diameter of the nickel crystallites measured in their oxide forms. The average diameter of nickel crystallites in oxide form is determined by X-ray diffraction from the width of the diffraction line at the angle 2theta = 43 ° (i.e. in the crystallographic direction [ 200]) using Scherrer's relation. This method, used in X-ray diffraction on powders or polycrystalline samples which connects the half-height width of the diffraction peaks to the particle size, is described in detail in the reference: Appl. Cryst. (1978), 11, 102-113 "Scherrer after sixty years: A survey and some new results in the determination of crystallite size", JI Langford and AJC Wilson. In the following, groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

Description of the catalyst preparation process

In general, the process for preparing the catalyst comprises the following steps:

a) a calcined aluminous porous oxide is prepared;

b) the aluminized calcined porous oxide obtained in step a) is kneaded with a solution resulting from the mixing of one or more solution (s) comprising at least one nickel precursor and at least one solution comprising at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one amine function to obtain a paste, the molar ratio between said organic compound and the nickel element being between 0.01 and 5.0 mol / mol;

c) shaping the paste obtained in step b);

Advantageously, the calcined aluminous porous oxide is obtained from a specific alumina gel. The particular porous distribution observed in the catalyst is in particular due to the process of preparation from the specific alumina gel.

Step al of calcined aluminum oxide preparation

The calcined aluminic oxide can be synthesized by various methods known to those skilled in the art. For example, a process for obtaining a gel consisting of a precursor of the gamma-oxy (hydroxide) aluminum type (AIO (OH), otherwise known as boehmite, is used, for example the alumina gel can be obtained by precipitation of basic and / or acid solutions of aluminum salts induced by pH change or any other method known to those skilled in the art This method is described in particular by P. Euzen, P. Raybaud, X. Krokidis, H. Toulhoat, JL The Loarer, JP Jolivet, C. Froidefond, Alumina, in Handbook of Porous Solids, Eds F. Schüth, Sing KSW, J. Weitkamp, Wiley-VCH, Weinheim, Germany, 2002, pp. 1591-1677.

Particularly preferably, the porous aluminum oxide is prepared from specific alumina gels prepared according to particular modes of preparation as described below.

Embodiment 1:

According to a first variant, the calcined aluminous porous oxide used in the context of the catalyst preparation process according to the invention is obtained by carrying out the following steps:

a1) a first step of precipitation, in an aqueous reaction medium, of at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide, and of at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid and nitric acid, wherein at least one of the basic precursors or acid comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain a first step progress rate of between 5 and 13%, the feed rate being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said first step of precipitation over the qu total amount of alumina formed at the end of step a3) of the preparation process, said step operating at a temperature of between 20 and 90 ° C and for a time of between 2 minutes and 30 minutes;

a3) a second step of precipitating the suspension obtained at the end of the heating step a2) by adding to the suspension at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, acid hydrochloric acid and nitric acid, wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10, 5 and the debit of the Aluminum-containing acidic and basic precursors are adjusted to obtain a second stage progress rate of between 87 and 95%, the feed rate being defined as the proportion of alumina formed in Al ₂ equivalent 0 ₃ during said second precipitation step relative to the total amount of alumina formed at the end of step a3) of the preparation process, said step operating at a temperature between 40 and 90 ° C and during a duration between 2 minutes and 50 minutes;

a5) a step of drying said alumina gel obtained in step a4) to obtain a powder; for example at a temperature between 20 and 200 ° C and for a period of between 8 h and 15 h;

a6) a step of heat treatment of the powder obtained at the end of step a5) between 500 and 1000 ° C, for a duration of between 2 and 10 h, in the presence or absence of a flow of air containing up to 60% water volume to obtain a calcined aluminous porous oxide.

The rate of progress for each of the precipitation stages is defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said first or second precipitation stage relative to the total amount of alumina formed in Al ₂ equivalent. 0 ₃ at the end of the two precipitation steps and more generally at the end of the steps of preparation of the alumina gel and in particular at the end of step a3) of the preparation process according to the invention.

Embodiment 2

According to a second variant, the calcined aluminous porous oxide used in the context of the process for preparing the catalyst according to the invention is obtained by carrying out the following steps:

a1 ') a step of dissolving an aluminum acid precursor chosen from aluminum sulphate, aluminum chloride and aluminum nitrate in water, at a temperature of between 20 and 90 ° C, at a pH of between 0.5 and 5, for a period of between 2 and 60 minutes,

a2 ') a step of adjusting the pH by adding to the suspension obtained in step a1') at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide, at a temperature between 20 and 90 ° C, and at a pH of between 7 and 10, for a period of between 5 and 30 minutes,

a5 ') a step of drying said alumina gel obtained in step a4') to obtain a powder, said drying step being operable at a temperature between 120 and 300 ° C, very preferably at a temperature between 150 and 250 ° C for 2 to 16 hours;

a6 ') a step of heat treatment of the powder obtained at the end of step a5') at a temperature of between 500 and 1000 ° C., with or without a flow of air containing up to 60 % by volume of water, for a period of between 2 and 10 hours, to obtain a calcined aluminous porous oxide.

Embodiment 3:

According to a third variant, the calcined aluminous porous oxide used in the context of the process for preparing the catalyst according to the invention is obtained by carrying out the following steps:

a1 ") at least a first step of precipitating alumina, in aqueous reaction medium, of at least one basic precursor chosen from sodium aluminate, potassium aluminate, aqueous ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, in wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium between 8.5 and 10.5 and the flow rate of the aluminum-containing acidic and basic precursor (s) is adjusted so as to obtain a progress rate of said first step of between 40 and 100%, the rate of advancement being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said first precipitation step relative to the total amount of alumina formed at the end of step c) of the preparation process, said first precipitation stage operating at a temperature between 10 and 50 ° C, and for a period of between 2 minutes and 30 minutes;

a4 ") a step of drying the alumina gel obtained at the end of step a3") to obtain a powder; said drying step being carried out at a temperature between 20 and 250 ° C, preferably between 50 and 200 ° C, for a period of between 1 day and 3 weeks, preferably between 2 hours and 1 week and even more preferably between 5 hours and 48 hours;

a5 ") a step of heat treatment of the powder obtained at the end of step a4") at a temperature of between 500 and 1000 ° C., with or without a flow of air containing up to 60 % by volume of water, for a period of between 2 and 10 h, to obtain a calcined aluminous porous oxide.

In general terms, the term "advancement rate" of the nth precipitation stage means the percentage of alumina formed in Al ₂ 0 ₃ equivalent in said nth stage, relative to the total quantity of alumina formed. at the end of all the precipitation steps and more generally after the steps of preparation of the alumina gel.

In the case where the progress rate of said precipitation step a1 ") is 100%, said precipitation step a1"") generally makes it possible to obtain a suspension of alumina having a concentration of Al ₂ O ₃ included between 20 and 100 g / l, preferably between 20 and 80 g / l, preferably between 20 and 50 g / l.

Step bl Comalaxaae

In this step, the calcined aluminous porous oxide obtained in step a) is mixed with a solution resulting from a mixture of one or more solution (s) comprising a nickel precursor and at least one solution comprising at least one organic compound comprising less a carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one amine function to obtain a paste, the molar ratio between the said organic compound and the nickel element being between 0.01 and 5.0 mol / mol.

The solution (s) comprising a nickel precursor may be aqueous or consist of an organic solvent or a mixture of water and water. minus an organic solvent (for example ethanol or toluene). Preferably, the solution is aqueous. The pH of this solution may be modified by the possible addition of an acid. According to another preferred variant, the aqueous solution may contain ammonia or ammonium ions NH ₄ ⁺ .

Preferably, said nickel precursor is introduced in aqueous solution, for example in the form of nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, complexes formed by a polyacid or an acid-alcohol and its salts, complexes formed with acetylacetonates, or any other soluble inorganic derivative in aqueous solution, which is brought into contact with said calcined aluminous porous oxide. Preferably, nickel precursor nickel nitrate, nickel chloride, nickel acetate or nickel hydroxycarbonate is advantageously used. Very preferably, the nickel precursor is nickel nitrate or nickel hydroxycarbonate.

According to another preferred variant, said nickel precursor is introduced into an ammoniacal solution by introducing a nickel salt, for example nickel hydroxide or nickel carbonate, into an ammoniacal solution or into an ammonium carbonate or ammonium carbonate solution. ammonium hydrogen carbonate.

The amounts of the nickel precursor (s) introduced into the solution are chosen such that the total nickel content is between 1 and 65% by weight, preferably between 5 and 55% by weight, preferably between 8 and 40% by weight. % by weight, and more preferably between 10 and 35% by weight, more preferably between 12 and 35% by weight, more preferably between 15 and 35% by weight, and more preferably between 18 and 35% by weight. 32% by weight of said element relative to the total mass of the catalyst. The nickel contents are generally adapted to the targeted hydrogenation reactions as described above. Said solution (s) containing at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one an amine function may be aqueous or organic (for example methanol or ethanol or phenol or acetone or toluene or dimethylsulfoxide (DMSO)) or be constituted a mixture of water and at least one organic solvent. The said organic compound (s) is (are) previously at least partially dissolved in the said solution (s) at the desired concentration. Preferably, said solution (s) is (are) aqueous or contains ethanol. Even more preferably, said solution is aqueous. The pH of said solution may be modified by the possible addition of an acid or a base.

Comalaxing is advantageously carried out in a kneader, for example a "Brabender" kneader, well known to those skilled in the art. The calcined alumina powder obtained in step a) is placed in the tank of the kneader. Then the solution resulting from the mixing of one or more solution (s) comprising at least one nickel precursor and at least one solution comprising at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one amine function, and optionally deionized water, is added to the syringe or with any other means for a period of a few minutes, typically about 2 minutes at a given kneading speed. After obtaining a paste, kneading can be continued for a few minutes, for example about 15 minutes at 50 rpm.

Said solution resulting from mixing can also be added in several times during this phase of comalaxing.

A) Organic compound comprising at least one carboxylic acid function

In one embodiment of the invention, the organic compound comprises at least one carboxylic acid function. The molar ratio of said organic compound comprising at least one carboxylic acid function is between 0.01 and 5.0 mol / mol, preferably between 0.05 and 2.0 mol / mol, more preferably between 0.1 and 1 , 5 mol / mol and even more preferably between 0.3 and 1, 2 mol / mol, with respect to the nickel element.

Said organic compound comprising at least one carboxylic acid function may be a saturated or unsaturated aliphatic organic compound or an aromatic organic compound. Preferably, the aliphatic organic compound, saturated or unsaturated, comprises between 1 and 9 carbon atoms, preferably between 2 and 7 carbon atoms. Preferably, the aromatic organic compound comprises between 7 and 10 carbon atoms, preferably between 7 and 9 carbon atoms.

Said aliphatic organic compound, saturated or unsaturated, or said aromatic organic compound, comprising at least one carboxylic acid function may be chosen from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids.

In a particular embodiment of the invention, said organic compound is a saturated aliphatic monocarboxylic acid, the aliphatic chain being linear or branched or cyclic. When the organic compound is a saturated linear monocarboxylic acid, it is preferably selected from formic acid, acetic acid, propionic acid, butanoic acid, valeric acid, hexanoic acid, heptanoic, octanoic acid, nonanoic acid. When the organic compound is a saturated branched monocarboxylic acid, it is preferably chosen from isobutyric acid, pivalic acid, methyl-4-octanoic acid, methyl-3-valeric acid, methyl 4-valeric acid, methyl-2-valeric acid, isovaleric acid, 2-ethyl-hexanoic acid, 2-methyl-butyric acid, 2-ethyl-butyric acid, propyl- 2-valerianic, valproic acid, in any of their isomeric forms. When the organic compound is a saturated cyclic monocarboxylic acid, it is preferably selected from cyclopentane carboxylic acid, cyclohexane carboxylic acid.

In a particular embodiment of the invention, said organic compound is an unsaturated aliphatic monocarboxylic acid, the aliphatic chain being linear or branched or cyclic, preferably selected from methacrylic acid, acrylic acid, vinylacetic acid, crotonic acid, isocrotonic acid, pentene-2-oic acid, penten-3-oic acid, pentene-4-oic acid, tiglic acid, angelic acid, acid sorbic acid, acetylene carboxylic acid, in any of their isomeric forms.

In a particular embodiment of the invention, said organic compound is an aromatic monocarboxylic acid, preferably selected from benzoic acid, methylbenzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, ethylbenzoic acid, o-tolylacetic acid, phenylacetic acid, phenyl-2-propionic acid, phenyl-3-propionic acid, vinyl-4-benzoic acid, phenylacetylenecarbonic acid , cinnamic acid, in any of their isomeric forms. In a particular embodiment of the invention, said organic compound is a saturated or unsaturated aliphatic dicarboxylic acid, the aliphatic chain being linear or branched or cyclic.

When the organic compound is a saturated linear dicarboxylic acid, it is preferably chosen from ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), butanedioic acid (succinic acid), pentanedioic acid (acid glutaric), hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid), octanedioic acid (suberic acid), nonanedioic acid (azelaic acid). When the organic compound is a saturated branched dicarboxylic acid, it is preferably chosen from methyl-2-glutaric acid, methyl-3-glutaric acid, dimethyl-3,3-glutaric acid and dimethyl acid. 2,2-glutaric acid, butane-1,2-dicarboxylic acid, in any of their isomeric forms.

When the organic compound is a cyclic saturated dicarboxylic acid, it is preferably selected from cyclohexanedicarboxylic acid, pinic acid, in any of their isomeric forms.

Preferably, said organic compound is chosen from ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), butanedioic acid (succinic acid) and pentanedioic acid (glutaric acid). 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, in any of their isomeric forms. Even more preferably, said organic compound is chosen from ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), butanedioic acid (succinic acid) and pentanedioic acid (glutaric acid).

When the organic compound is an unsaturated, linear or branched or cyclic dicarboxylic acid, it is preferably chosen from (Z) -butenedioic acid (maleic acid), (E) -butenedioic acid (fumaric acid), pent-2-enedioic acid (glutaconic acid), (2E-4E) -hexa-2,4-dienediioic acid (muconic acid), mesaconic acid, citraconic acid, acetylenedicarboxylic acid, acid methylene-2-succinic acid (itaconic acid), hexadiene-2,4-dioic acid, in any of their isomeric forms.

Preferably, said organic compound is chosen from (Z) -butenedioic acid (maleic acid), (E) -butenedioic acid (fumaric acid), pent-2-enedioic acid (glutaconic acid), mesaconic acid, citraconic acid, methylene-2-succinic acid (itaconic acid), in any of their isomeric forms. Even more preferably, said organic compound is chosen from (Z) -butenedioic acid (acid maleic), (E) -butenedioic acid (fumaric acid), pent-2-enedioic acid (glutaconic acid).

In a particular embodiment of the invention, said organic compound is an aromatic dicarboxylic acid, preferably selected from benzene-1,2-dicarboxylic acid (phthalic acid), benzene-1,3-dicarboxylic acid ( isophthalic acid), benzene-1,4-dicarboxylic acid (terephthalic acid), phenylsuccinic acid, in any of their isomeric forms. Preferably, said organic compound is benzene-1,2-dicarboxylic acid (phthalic acid).

In a particular embodiment of the invention, said organic compound is an aliphatic tricarboxylic acid, saturated or unsaturated, or aromatic, preferably selected from propanetricarboxylic acid-1,2,3 (tricarballylic acid), butanetricarboxylic acid 1, 2,4, propene-tricarboxylic acid-1,2,3 (aconitic acid), benzenetricarboxylic acid-1,3,5 (trimesic acid), benzenetricarboxylic acid-1,2,4, in any of their isomeric forms. Preferably, said organic compound is chosen from propanetricarboxylic acid-1,2,3 (tricarballylic acid), butanetricarboxylic acid-1,2,4, propene-tricarboxylic acid-1,2,3 (aconitic acid). ), benzenetricarboxylic acid-1,2,4, in any of their isomeric forms.

In a particular embodiment of the invention, said organic compound is a saturated or unsaturated, or aromatic, aliphatic tetracarboxylic acid, preferably selected from methanetetracarboxylic acid, butanetetracarboxylic acid-1, 2,3,4, ethylenetetracarboxylic acid, benzenetetracarboxylic acid-1,2,4,5, in any of their isomeric forms. Preferably, said organic compound is selected from butanetetracarboxylic acid-1, 2, 3, 4, benzenetetracarboxylic acid-1, 2, 4, 5, in any of their isomeric forms.

In another embodiment of the invention, said organic compound may comprise at least one second functional group chosen from ethers, hydroxyls, ketones and esters. Advantageously, said organic compound comprises at least one carboxylic acid function and at least one hydroxyl function, or at least one carboxylic acid function and at least one ether function, or at least one carboxylic acid function and at least one ketone function. Advantageously, said compound organic can comprise at least three different functional groups selected from at least one carboxylic acid function, at least one hydroxide function and at least one functional group different from the carboxylic acid and hydroxyl functions, such as an ether function or a ketone function.

Among the organic compounds comprising at least one carboxylic acid function and at least one hydroxyl group, mention may be made of the hydroxy acids of the monocarboxylic acids, the hydroxy acids of the dicarboxylic acids or of the polycarboxylic acids, the dihydroxy acids of the monocarboxylic acids or of the polycarboxylic acids, the trihydroxy acids of the monocarboxylic acids or polycarboxylic acids, and more generally polyhydroxyacids monocarboxylic acids or polycarboxylic acids, the carbon chain of said acids can be saturated aliphatic (linear, branched or cyclic), or unsaturated aliphatic (linear, branched or cyclic) or may contain at least one aromatic ring. Preferably, said organic compound is chosen from hydroxy acids or dihydroxy acids of monocarboxylic acids or dicarboxylic acids or tricarboxylic acids.

When the organic compound is a hydroxy acid of a monocarboxylic acid, it is preferably chosen from hydroxyacetic acid (glycolic acid), 2-hydroxypropanoic acid (lactic acid), hydroxy-2-isobutyric acid or the other α-hydroxy acids, 3-hydroxypropanoic acid, 3-hydroxy-butyric acid, 3-hydroxypentanoic acid, 3-hydroxy-3-isobutyric acid, 3-hydroxy-3-methylbutanoic acid, or the other b-hydroxy acids, 4-hydroxy-butyric acid or other g-hydroxy acids, mandelic acid, 3-phenyllactic acid, tropic acid, hydroxybenzoic acid, salicylic acid, acid ( hydroxy-2-phenyl) -acetic acid, (3-hydroxy-phenyl) -acetic acid, (4-hydroxy-phenyl) -acetic acid, coumaric acid, in any of their isomeric forms. Preferably, said organic compound is chosen from hydroxyacetic acid (glycolic acid), 2-hydroxypropanoic acid (lactic acid), 3-hydroxypropanoic acid, 3-hydroxy-butyric acid, hydroxy-acid and 3-isobutyric, mandelic acid, 3-phenyllactic acid, tropic acid, salicylic acid, in any of their isomeric forms. Even more preferably, said organic compound is chosen from hydroxyacetic acid (glycolic acid), 2-hydroxypropanoic acid (lactic acid), 3-hydroxypropanoic acid, hydroxy-3-butyric acid, hydroxy-3-isobutyric acid.

When the organic compound is a hydroxy acid of a polycarboxylic acid, it is preferably chosen from 2-hydroxypropanedioic acid (tartronic acid), 2-hydroxybutanedioic acid (malic acid), acetolactic acid or the others. hydroxy acids or b-hydroxy acids or g-hydroxy acids of dicarboxylic acids, 5-hydroxy-isophthalic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), isocitric acid, homocitric acid , the homoisocitric acid or the other α-hydroxy acids or b-hydroxy acids or α-hydroxy acids of the tricarboxylic acids, in any of their isomeric forms. Preferably, said organic compound is chosen from 2-hydroxypropanedioic acid (tartronic acid), 2-hydroxybutanedioic acid (malic acid), acetolactic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), isocitric acid, homocitric acid, homoisocitric acid, in any of their isomeric forms. Even more preferably, said organic compound is chosen from 2-hydroxypropanedioic acid (tartronic acid), 2-hydroxybutanedioic acid (malic acid), acetolactic acid, 2-hydroxypropane-1, 2 acid, 3-tricarboxylic acid (citric acid).

When the organic compound is a dihydroxy acid of a monocarboxylic acid, it is preferably chosen from glyceric acid, 2,3-dihydroxy-3-methylpentanoic acid, pantoic acid or the other α, α-dihydroxy acids or α, β-dihydroxy acids or α,--dihydroxy acids, 3,5-dihydroxy-3-methylpentanoic acid (mevalonic acid), or the other b, b-dihydroxy acids or b, g-dihydroxy acids or g, g-dihydroxy acids, Bis (hydroxymethyl) acid

2.2-propionic acid, 2,3-dihydroxybenzoic acid, α-resorcylic acid, b-resorcylic acid, g-resorcylic acid, gentisic acid, protocatechic acid, orselinic acid, l homogentisic acid, caffeic acid, in any of their isomeric forms. Preferably, said organic compound is chosen from glycerolic acid,

2,3-dihydroxy-3-methylpentanoic acid, pantoic acid, 2,3-dihydroxybenzoic acid, b-resorcylic acid, g-resorcylic acid, gentisic acid, orsellinic acid, under one any of their isomeric forms. Even more preferably, said organic compound is chosen from glyceric acid, 2,3-dihydroxy-3-methylpentanoic acid and pantoic acid. When the organic compound is a dihydroxy acid of a polycarboxylic acid, it is preferably chosen from dihydroxymalonic acid, 2,3-dihydroxybutanedioic acid (tartaric acid) or the other α, α-dihydroxyacids or α, β-dihydroxyacids or α, β-dihydroxy acids or β, β-dihydroxy acids or β, β-dihydroxy acids or α-dihydroxy acids of the dicarboxylic acids, hydroxycitric acid, in any of their isomeric forms. Preferably, said organic compound is chosen from dihydroxymalonic acid, 2,3-dihydroxybutanedioic acid (tartaric acid) and hydroxycitric acid, in any of their isomeric forms. Even more preferably, said organic compound is chosen from dihydroxymalonic acid, 2,3-dihydroxybutanedioic acid (tartaric acid).

When the organic compound is a polyhydroxy acid of a monocarboxylic acid or of a polycarboxylic acid, it is preferably selected from shikimic acid, trihydroxybenzoic acid, gallic acid, phloroglucinic acid, pyrogallol carboxylic acid, quinic acid, gluconic acid, mucic acid, saccharic acid, in any of their isomeric forms. Preferably, said organic compound is chosen from trihydroxybenzoic acid, quinic acid, gluconic acid, mucic acid and saccharic acid, in any of their isomeric forms. Even more preferably, said organic compound is chosen from quinic acid, gluconic acid, mucic acid and saccharic acid.

Among the organic compounds comprising at least one carboxylic acid function and at least one ether function, mention may be made of 2-methoxyacetic acid, 2,2'-oxydiacetic acid (diglycolic acid), 4-methoxybenzoic acid, isopropoxy-4-benzoic acid, methoxy-3-phenylacetic acid, methoxy-3-cinnamic acid, methoxy-4-cinnamic acid, 3,4-dimethoxycinnamic acid, veratric acid, acid tetrahydrofuran-2-carboxylic acid, furan-3-carboxylic acid, 2,5-dihydro-3,4-furan dicarboxylic acid acid, according to any of their isomeric forms. Preferably, said organic compound is 2,2'-oxydiacetic acid (diglycolic acid).

Among the organic compounds comprising at least one carboxylic acid function and at least one ketone functional group, mention may be made of glyoxylic acid, 2-oxopropanoic acid (pyruvic acid), 2-oxobutanoic acid and 3-oxopentanoic acid. , 3-methyl-2-oxobutanoic acid, 4-methyl-2-oxopentanoic acid, phenylglyoxylic acid, phenylpyruvic acid, mesoxalic acid, 2-oxoglutaric acid, 2-oxohexanedioic acid, oxalosuccinic acid or the other α-keto acids of monocarboxylic acids or polycarboxylic acids, acetylacetic acid, acetonedicarboxylic acid, or other β-ketoacids of monocarboxylic acids or polycarboxylic acids, 4-oxopentanoic acid (levulinic acid) or the other α-keto acids of monocarboxylic acids or polycarboxylic acids, acetyl-4-benzoic acid, dioxosuccinic acid , 4-maleylacetoacetic acid or the other polyketo acids of monocarboxylic acids or polycarboxylic acids, according to any of their isomeric forms. Preferably, said organic compound is chosen from glyoxylic acid, 2-oxopropanoic acid (pyruvic acid), 2-oxobutanoic acid, 3-methyl-2-oxobutanoic acid, phenylglyoxylic acid, phenylpyruvic acid, mesoxalic acid, 2-oxoglutaric acid, 2-oxohexanedioic acid, oxalosuccinic acid, acetylacetic acid, acetonedicarboxylic acid, 4-oxopentanoic acid (levulinic acid), dioxosuccinic acid, according to any one of their isomeric forms. Even more preferably, said organic compound is chosen from glyoxylic acid, 2-oxopropanoic acid (pyruvic acid), 2-oxobutanoic acid, 3-methyl-2-oxobutanoic acid and mesoxalic acid. , 2-oxoglutaric acid, acetylacetic acid, acetonedicarboxylic acid, 4-oxopentanoic acid (levulinic acid), dioxosuccinic acid.

Among the organic compounds comprising at least one carboxylic acid function and at least one ester function, mention may be made of acetylsalicylic acid.

Among the organic compounds comprising at least one carboxylic acid function, at least one hydroxide functional group and at least one ether functional group, mention may be made of 4-hydroxy-3-methoxybenzoic acid (vanillic acid), syringic acid and acid. glucuronic acid, galacturonic acid, ferulic acid, sinapic acid, according to any of their isomeric forms. Preferably, said organic compound is chosen from 4-hydroxy-3-methoxybenzoic acid (vanillic acid), glucuronic acid and galacturonic acid, according to any of their isomeric forms.

Among the organic compounds comprising at least one carboxylic acid function, at least one hydroxide functional group and at least one ketone functional group, mention may be made of hydroxypyruvic acid, acetolactic acid, iduronic acid, ulosonic acid and acid. meconic, 4-hydroxyphenylpyruvic acid, according to any of their forms isomers. Preferably, said organic compound is selected from hydroxypyruvic acid, acetolactic acid, iduronic acid, meconic acid, according to any of their isomeric forms.

Among all the preceding embodiments, said organic compound comprising at least one carboxylic acid function is preferably chosen from ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), butanedioic acid (succinic acid), pentanedioic acid (glutaric acid). 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, (Z) -butenedioic acid (maleic acid), (E) -butenedioic acid (fumaric acid), pent-2-acid -enedioic acid (glutaconic acid), mesaconic acid, citraconic acid, methylene-2-succinic acid (itaconic acid), benzene-1, 2-dicarboxylic acid (phthalic acid), propanetricarboxylic acid- 1, 2,3 (tricarballylic acid), butanetricarboxylic acid-1,2,4, propene-tricarboxylic acid-1,2,3 (aconitic acid), benzenetricarboxylic acid-1,2,4,4 1,2,3,4-butanetetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, hydroxyacetic acid (glycolic acid), 2-hydroxypropanoic acid (lactic acid), 3- hydroxypropanoic acid, 3-hydroxy-butyric acid, 3-hydroxy-isobutyric acid, mandelic acid, 3-phenyllactic acid, tropic acid, salicylic acid, acid glycerol, 2,3-dihydroxy-3-methylpentanoic acid, pantoic acid, 2,3-dihydroxybenzoic acid, b-resorcylic acid, g-resorcylic acid, gentisic acid, orsellinic acid, dihydroxymalonic acid, 2,3-dihydroxybutanedioic acid (tartaric acid), hydroxycitric acid, trihydroxybenzoic acid, quinic acid, gluconic acid, mucic acid, saccharic acid 2,2'-oxydiacetic acid (diglycolic acid). glyoxylic acid, 2-oxopropanoic acid (pyruvic acid), 2-oxobutanoic acid, 3-methyl-2-oxobutanoic acid, phenylglyoxylic acid, phenylpyruvic acid, mesoxalic acid, 2-oxoglutaric acid, 2-oxohexanedioic acid, oxalosuccinic acid, acetylacetic acid, acetonedicarboxylic acid, 4-oxopentanoic acid (levulinic acid), dioxosuccinic acid, 4-hydroxy acid 3-methoxybenzoic acid (vanillic acid), glucuronic acid, galacturonic acid, hydroxypyruvic acid, acetolactic acid, iduronic acid, meconic acid, according to any of their isomeric forms.

Among all the preceding embodiments, said organic compound comprising at least one carboxylic acid function is more preferably chosen from acid ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), butanedioic acid (succinic acid), pentanedioic acid (glutaric acid), (Z) - butenedioic acid (maleic acid), acid ( E) -butenedioic acid (fumaric acid), pent-2-enedioic acid (glutaconic acid), hydroxyacetic acid (glycolic acid), 2-hydroxypropanoic acid (lactic acid), 3-hydroxypropanoic acid, 3-hydroxy-butyric acid, 3-hydroxy-isobutyric acid, 2-hydroxypropanedioic acid (tartronic acid), 2-hydroxybutanedioic acid (malic acid), acetolactic acid, 2-hydroxypropane acid 1,2,3-tricarboxylic acid (citric acid), glyceric acid, 2,3-dihydroxy-3-methylpentanoic acid, pantoic acid, dihydroxymalonic acid, 2,3-dihydroxybutanedioic acid ( tartaric acid), quinic acid, gluconic acid, mucic acid, saccharic acid, glyoxylic acid, 2-oxopropanoic acid (pyruvic acid) e), 2-oxobutanoic acid, 3-methyl-2-oxobutanoic acid, mesoxalic acid, 2-oxoglutaric acid, acetylacetic acid, acetonedicarboxylic acid, 4-oxopentanoic acid ( levulinic acid), dioxosuccinic acid. Even more preferentially, the organic compound comprising at least one carboxylic acid function is chosen from ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), pentanedioic acid (glutaric acid), hydroxyacetic acid (acid glycolic acid), 2-hydroxypropanoic acid (lactic acid), 2-hydroxypropanedioic acid (tartronic acid), 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), 2,3-acid - dihydroxybutanedioic acid (tartaric acid), 2-oxopropanoic acid (pyruvic acid), 4-oxopentanoic acid (levulinic acid).

B) Organic compound comprising at least one alcohol function

In another embodiment according to the invention, the organic compound comprises at least one alcohol function. The molar ratio of said organic compound comprising at least one alcohol function with respect to the nickel element is between 0.01 and 5.0 mol / mol, preferably between 0.05 and 1.5 mol / mol, more preferably between 0.08 and 0.9 mol / mol.

Preferably, said organic compound comprises between 2 and 20 carbon atoms, preferably between 2 and 12 carbon atoms, and even more preferably between 2 and 8 carbon atoms. In one embodiment of the invention, the organic compound comprises a single alcohol function (mono-alcohol). Preferably, the organic compound is chosen from methanol, ethanol, propanol, butanol, pentanol, hexanol, 2-propyn-1-ol, geraniol, menthol, phenol and cresol. in any of their isomeric forms. More preferentially, said organic compound is chosen from methanol, ethanol and phenol.

In another embodiment of the invention, the organic compound comprises at least two alcohol functions (diol or more generally polyol). Preferably, the organic compound is selected from ethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol , heptane-1,7-diol, octane-1,8-diol, propane-1,2-diol, butane-1,2-diol, butane-2,3-diol, butane 1,3-diol, pentane-1,2-diol, pentane-1,3-diol, pentane-2,3-diol, pentane-2,4-diol, 2-ethylhexane-1, 3-diol (hexhexadiol), p-menthane-3,8-diol, 2-methylpentane-2,4-diol, but-2-yn-1,4-diol, 2,3,4-trihydroxypentane , 2,2-dihydroxyhexane, 2,2,4-trihydroxyhexane, glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, dulcitol, allitol, gluciotol, tolitol, fucitol, iditol, volemitol, inositol, in any of their isomeric forms. More preferably, said organic compound is chosen from ethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol and hexane-1,6-diol. , glycerol, xylitol, mannitol, sorbitol, in any of their isomeric forms.

In another embodiment according to the invention, the organic compound is an aromatic organic compound comprising at least two alcohol functional groups. Preferably, the organic compound is selected from pyrocatechol, resorcinol, hydroquinol, pyrogallol, phloroglucinol, hydroxyquinol, tetrahydroxybenzene, benzenehexol, in any of their isomeric forms. More preferably, said organic compound is selected from pyrocatechol, resorcinol, hydroquinol.

In another embodiment according to the invention, the organic compound may be selected from diethylene glycol, triethylene glycol, tetraethylene glycol, or more generally polyethylene glycol having the formula H (OC ₂ H ₄ ) _n OH with n greater than at 4 and having an average molecular weight of less than 20000 g / mol. More preferably, said organic compound is selected from diethylene glycol, triethylene glycol, polyethylene glycol having an average molecular weight of less than 600 g / mol. In another embodiment according to the invention, the organic compound is a monosaccharide of formula C _n (H ₂ O) _p with n of between 3 and 12, preferably between 3 and 10. Preferably, the organic compound is selected from glyceraldehyde, dihydroxyacetone, erythrose, threose, erythrulose, lyxose, arabinose, xylose, ribose, ribulose, xylulose, glucose, mannose, sorbose, galactose, fructose, allose, altrose, gulose, idose, talose, psicose, tagatose, sedoheptulose, mannoheptulose, in any of their isomeric forms. More preferably, said organic compound is selected from glucose, mannose, fructose, in any of their isomeric forms.

In another embodiment of the invention, the organic compound is a disaccharide or a trisaccharide, or a derivative of a monosaccharide, selected from sucrose, maltose, lactose, cellobiose, gentiobiose, inulobiosis, isomaltose, isomaltulose, kojibiose, lactulose, laminaribiose, leucrose, maltulose, melibiose, nigerose, robinose, rutinose, sophorose, trehalose, trehalulose, turanose, erlose , fucosyllactose, gentianose, inulotriose, kestose, maltotriose, mannotriose, melezitose, neokestose, panose, raffinose, rhamninose, maltitol, lactitol, isomaltitol, isomaltulose, any of their isomeric forms. More preferably, said organic compound is selected from sucrose, maltose, lactose, in any of their isomeric forms.

In another embodiment according to the invention, the organic compound comprises at least one alcohol function, at least one ketone functional group and at least one unsaturated heterocyclic functional group, preferably chosen from isomaltol, maltol, ethylmaltol and the acid. dehydroacetic acid, kojic acid, erythorbic acid, in any of their isomeric forms.

Among all the preceding embodiments, said organic compound comprising at least one alcohol function is preferably chosen from methanol, ethanol, propanol, butanol, pentanol, hexanol and 2-propyn-1-ol. , geraniol, menthol, phenol, cresol, ethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1 , 6-diol, heptane-1,7-diol, octane-1,8-diol, propane-1,2-diol, butane-1,2-diol, 2,3-butane diol, butane-1,3-diol, pentane-1,2-diol, pentane-1,3-diol, pentane-2,3-diol, pentane-2,4-diol, 2- ethylhexane-1,3-diol, p-menthane-3,8-diol, 2-methylpentane-2,4-diol, but-2-yn-1,4-diol, 2,3,4-trihydroxypentane, 2,2-dihydroxyhexane, 2,2,4-trihydroxyhexane, glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, dulcitol, allitol, gluciotol, tolitol, fucitol, iditol, volemitol, inositol, pyrocatechol, resorcinol, hydroquinol, pyrogallol, phloroglucinol, hydroxyquinol, tetrahydroxybenzene, benzenehexol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having the formula H (OC2H ₄ ) _n OH with n greater than 4 and having an average molecular weight of less than 20000 g / mol, glyceraldehyde, dihydroxyacetone, erythrose, threose, erythrulose, lyxose, arabinose, xylose, ribose, ribulose, xylulose, glucose, mannose, sorbose, galactose, fructose, allose, altrose, gulose, idose, talose, psicose, t agatose, sedoheptulose, mannoheptulose, sucrose, maltose, lactose, cellobiose, gentiobiose, inulobiosis, isomaltose, isomaltulose, kojibiose, lactulose, laminaribiose, leucrose, maltulose, melibiose, nigerose, robinose, rutinose, sophorose, trehalose, trehalulose, turanose, erlose, fucosyllactose, gentianose, inulotriose, kestose, maltotriose, mannotriose, melezitose, neokestosis, panose, raffinose, rhamninose, maltitol, lactitol, isomaltitol, isomaltulose, isomaltol, maltol, ethylmaltol, dehydroacetic acid, kojic acid, acid erythorbic acid, in any of their isomeric forms.

More preferably, said organic compound is selected from methanol, ethanol, phenol, ethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol , hexane-1,6-diol, glycerol, xylitol, mannitol, sorbitol, pyrocatechol, resorcinol, hydroquinol, diethylene glycol, triethylene glycol, polyethylene glycol having a lower average molecular weight at 600 g / mol, glucose, mannose, fructose, sucrose, maltose, lactose, in any of their isomeric forms.

C) Organic compound comprising at least one ester function

In another embodiment of the invention, the organic compound comprises at least one ester function. The molar ratio of said organic compound comprising at least one ester function with respect to the nickel element is between 0.01 and 5.0 mol / mol, preferably between 0.05 and 2.0 mol / mol, more preferably between 0.1 and 1.5 mol / mol and even more preferably between 0.3 and 1.2 mol / mol. Preferably, said organic compound comprises between 2 and 20 carbon atoms, preferably between 3 and 14 carbon atoms, and even more preferably between 3 and 8 carbon atoms.

According to the invention, said organic compound comprises at least one ester function. It may be chosen from an unsaturated linear or cyclic or cyclic carboxylic acid ester, or a cyclic or linear carbonic acid ester or a linear carbonic acid diester.

In the case of a cyclic carboxylic acid ester, the compound may be a saturated cyclic ester. We speak of a-lactone, b-lactone, g-lactone, d-lactone, c-lactone according to the number of carbon atoms in the heterocycle. Said compound may also be substituted by one or more alkyl group (s) or aryl (s) or alkyl (s) containing unsaturations. Preferably, said compound is a lactone containing between 4 and 12 carbon atoms, such as g-butyrolactone, g-valerolactone, d-valerolactone, g-caprolactone, d-caprolactone, Ge-caprolactone, g-caprolactone, -heptalactone, d-heptalactone, g-octalactone, d-octalactone, d-nonalactone, c-nonalactone, d-decalactone, g-decalactone, c-decalactone, d-dodecalactone, g-octalactone, -dodecalactone, in any of their isomeric forms. Even more preferably, said compound is a g-lactone or a d-lactone containing between 4 and 8 carbon atoms, g-butyrolactone, g-valerolactone, d-valerolactone, g-caprolactone, d-valerolactone, caprolactone, g-heptalactone, d-heptalactone, g-octalactone, d-octalactone, in any of their isomeric forms. Preferably, the compound is g-valerolactone.

In the case of an unsaturated cyclic ester (containing unsaturations in the ring) of carboxylic acid, the compound may be furan or pyrone or any of their derivatives, such as 6-pentyl-a-pyrone .

In the case of a linear carboxylic acid ester, the compound may be a compound having a single ester function corresponding to the empirical formula RCOOR ', in which R and R' are alkyl, linear, branched, or cyclic, or alkyl groups containing unsaturations, or alkyl groups substituted with one or more aromatic rings, or aryl groups, each containing between 1 and 15 carbon atoms, and which may be the same or different. The group R may also be the hydrogen atom H. Preferably, the group R '(of the alkoxy function COR') contains a number of carbon atoms less than or equal to that of the group R, more preferably the number of carbon atoms of said group R 'is between 1 and 6, even more preferably between 1 and 4. Said organic compound is preferably chosen from methyl methanoate, methyl acetate, methyl propanoate, methyl butanoate, methyl pentanoate, methyl hexanoate, methyl octanoate and methyl decanoate. methyl laurate, methyl dodecanoate, ethyl acetate, ethyl propanoate, ethyl butanoate, ethyl pentanoate, ethyl hexanoate. Preferably, the organic compound is methyl laurate.

In another embodiment according to the invention, the organic compound may be a compound comprising at least two carboxylic acid ester functions.

Advantageously, the carbon chain in which these carboxylic acid ester functions are inserted is a linear or branched or cyclic aliphatic carbon chain, saturated or possibly containing unsaturations, and contains between 2 and 15 carbon atoms and each R 'group ( each of the alkoxy functions COR ') may be a linear, branched or cyclic alkyl group, or an alkyl group containing unsaturations, or an alkyl group substituted with one or more aromatic rings, or an aryl group, and containing between 1 and 15 carbon atoms, preferably between 1 and 6 carbon atoms, even more preferably between 1 and 4 carbon atoms. The different groups R 'may be identical or different. Preferably, said compound is chosen from dimethyl oxalate, dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, diethyl oxalate, diethyl malonate and diethyl succinate. diethyl glutarate, diethyl adipate, dimethyl methyl succinate, dimethyl 3-methylglutarate, in any of their isomeric forms. More preferably, the compound is dimethyl succinate.

In another embodiment according to the invention, the organic compound may be a compound comprising at least one carboxylic acid ester function and at least one second functional group chosen from alcohols, ethers, ketones and aldehydes. Advantageously, said organic compound comprises at least one carboxylic acid ester function and at least one alcohol function.

Preferably, the carbon chain in which the carboxylic acid ester function (s) is inserted is a linear or branched or cyclic aliphatic carbon chain, which is saturated or may contain unsaturations, and contains between 2 and 15 carbon atoms. carbon and each R 'group (of each of the alkoxy functions COR') may be a linear, branched, or cyclic alkyl group, or an alkyl group containing unsaturations, or an alkyl group substituted by one or more aromatic rings, or an aryl group and containing between 1 and 15 carbon atoms, preferably between 1 and 6 carbon atoms, more preferably between 1 and 4 carbon atoms, the different groups R 'may be identical or different. This carbon chain contains at least one hydroxyl group, preferably between 1 and 6 hydroxyl groups.

Preferably, said compound is chosen from methyl glycolate, ethyl glycolate, butyl glycolate, benzyl glycolate, methyl lactate, ethyl lactate, butyl lactate, tert-lactate and butyl, ethyl 3-hydroxybutyrate, ethyl mandelate, dimethyl malate, diethyl malate, diisopropyl malate, dimethyl tartrate, diethyl tartrate, diisopropyl tartrate, trimethyl citrate triethyl citrate, in any of their isomeric form. More preferentially, said compound is dimethyl malate.

Advantageously, said organic compound comprises at least one carboxylic acid ester function and at least one ketone or aldehyde function. Preferably, the carbon chain in which the carboxylic acid ester function (s) is inserted is a linear or branched or cyclic aliphatic carbon chain, which is saturated or may contain unsaturations, and contains between 2 and 15 carbon atoms. carbon and each R 'group (of each of the alkoxy functions COR') can be a linear, branched, or cyclic alkyl group, or an alkyl group containing unsaturations, or an alkyl group substituted by one or more aromatic rings, or a aryl group, and containing between 1 and 15 carbon atoms, preferably between 1 and 6 carbon atoms, even more preferably between 1 and 4 carbon atoms, the different groups R 'may be identical or different. This carbon chain contains at least one ketone or aldehyde function, preferably between 1 and 3 ketone or aldehyde function (s). Preferably, the organic compound is an acetoacid.

In the case of a cyclic carbonic acid ester, the compound may be ethylene carbonate, propylene carbonate or trimethylene carbonate. Preferably, the compound is propylene carbonate.

In the case of a linear ester of carbonic acid, the compound may be dimethyl carbonate, diethyl carbonate or diphenyl carbonate. In the case of a linear diester of carbonic acid, the compound may be dimethyl dicarbonate, diethyl dicarbonate, di-tert-butyl dicarbonate.

Advantageously, said organic compound may comprise at least three different functional groups chosen from at least one ester function, at least one carboxylic acid function and at least one functional group other than the ester and carboxylic acid functions, such as an ether function or a ketone function.

Among all the preceding embodiments, said organic compound comprising at least one ester function is preferably chosen from a g-lactone or a d-lactone containing between 4 and 8 carbon atoms, g-butyrolactone, g-valerolactone, d-valerolactone, ε-caprolactone, ε-caprolactone, β-heptalactone, d-heptalactone, β-octalactone, d-octalactone, methyl methanoate, methyl acetate, methyl propanoate, methyl butanoate, methyl pentanoate, methyl hexanoate, methyl octanoate, methyl decanoate, methyl laurate, methyl dodecanoate, ethyl acetate, ethyl propanoate, ethyl butanoate, ethyl pentanoate, ethyl hexanoate, dimethyl oxalate, dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, sodium oxalate and the like. diethyl, diethyl malonate, succinate diethyl nate, diethyl glutarate, diethyl adipate, dimethyl methyl succinate, dimethyl 3-methylglutarate, methyl glycolate, ethyl glycolate, butyl glycolate, benzyl glycolate, lactate methyl lactate, ethyl lactate, butyl lactate, tert-butyl lactate, ethyl 3-hydroxybutyrate, ethyl mandelate, dimethyl malate, diethyl malate, diisopropyl malate, dimethyl tartrate, diethyl tartrate, diisopropyl tartrate, trimethyl citrate, triethyl citrate, ethylene carbonate, propylene carbonate, trimethylene carbonate, diethyl carbonate, diphenyl, dimethyl dicarbonate, diethyl dicarbonate, di-tert-butyl dicarbonate, in any of their isomeric form.

D) Organic compound comprising at least one amide function

In another embodiment according to the invention, the organic compound comprises at least one amide function, chosen from an acyclic amide function or a cyclic amide function, optionally comprising alkyl or aryl or alkyl substituents containing unsaturations. The amide functions may be chosen from primary, secondary or tertiary amides. The molar ratio of said organic compound comprising at least one amide function relative to the nickel element is between 0.01 and 1.5 mol / mol, preferably between 0.05 and 1.0 mol / mol, more preferably between 0.08 and 0.9 mol / mol.

According to a first variant, the organic compound comprises at least one acyclic amide function.

Said organic compound may comprise a single amide function and does not contain any other functional group, such as formamide, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N N, N-dibutylformamide, N, N-diisopropylformamide, N, N-diphenylformamide, acetamide, N-methylacetamide, N, N-dimethylmethanamide, N, N-diethylacetamide, N, N-dimethylpropionamide, propanamide, N-ethyl-N-methylpropanamide, benzamide, acetanilide, according to any of their isomeric forms. Preferably, said organic compound is chosen from formamide, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N- dimethylmethanamide, N, N-diethylacetamide, N, N-dimethylpropionamide, propanamide,

Said organic compound may comprise two amide functions and contains no other functional group, such as tetraacetylethylenediamine.

According to a second variant, the organic compound comprises at least one cyclic amide function, such as 1-formylpyrrolidine, 1-formylpiperidine, or a lactam function. Preferably, said organic compound is selected from β-lactam, β-lactam, β-lactam and ε-lactam and their derivatives, according to any of their isomeric forms. More preferably, said organic compound is selected from 2-pyrrolidone, N-methyl-2-pyrrolidone, β-lactam, caprolactam, according to any of their isomeric forms.

According to a third variant, said organic compound may comprise at least one amide function and at least one other function different from the amide function. Preferably, said organic compound comprises at least one amide functional group and at least one carboxylic acid functional group, such as acetylleucine, N-acetylaspartic acid, aminohippuric acid, N-acetylglutamic acid and 4-acetamidobenzoic acid. according to any of their isomeric forms. Preferably, said organic compound comprises at least one amide function and at least one alcohol function, such as glycolamide, lactamide, N, N-diethyl-2-hydroxyacetamide, 2-hydroxy-N-methylacetamide and 3-hydroxypropionamide. mandelamide, acetohydroxamic acid, butyrylhydroxamic acid, bucetin, according to any of their isomeric forms. Preferably, said organic compound is chosen from lactamide and glycolamide.

According to a fourth variant, the organic compound comprises at least one amide functional group and at least one additional nitrogen heteroatom, preferably chosen from urea, N-methylurea, N, N'-dimethylurea, 1,1 dimethylurea, tetramethylurea, according to any of their isomeric forms.

Among all the organic compounds comprising at least one amide function above, formamide, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, acetamide, are more particularly preferred. N-methylacetamide, N, N-dimethylmethanamide, N, N-diethylacetamide, N, N-dimethylpropionamide, propanamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, γ-lactam, caprolactam Acetylleucine, N-acetylaspartic acid, aminohippuric acid, N-acetylglutamic acid, 4-acetamidobenzoic acid, lactamide and glycolamide, urea, N-methylurea, N, N 1-dimethylurea, 1,1-dimethylurea, tetramethylurea according to any of their isomeric forms.

E) Organic compound comprising at least one amine function

In another embodiment of the invention, the organic compound comprises at least one amine function. The molar ratio of said organic compound comprising at least one amine function with respect to the nickel element is between 0.01 and 1.5 mol / mol, preferably between 0.05 and 1.0 mol / mol, more preferably between 0.08 and 0.9 mol / mol.

Said organic compound comprises between 1 and 20 carbon atoms, preferably between 1 and 14 carbon atoms, and even more preferably between 2 and 8 carbon atoms.

In one embodiment according to the invention, the organic compound comprises at least one amine function corresponding to the empirical formula C _x N _y H _z in which x is between 1 and 20, y = 1-x and z = 2- (2x + 2). Said organic compound may be chosen from a saturated or unsaturated aliphatic, cyclic, alicyclic, aromatic or heterocyclic amine, optionally comprising alkyl or aryl or alkyl substituents containing unsaturations. The amine functions can be chosen from primary, secondary or tertiary amines.

According to a first variant, the organic compound comprises a single amine function and does not contain any other functional group.

More particularly, said organic compound comprising a single amine function is chosen from aliphatic compounds, such as propylamine, ethylmethylamine, butylamine, dimethylisopropylamine, dipropylamine, diisopropylamine, octylamine, cyclic or alicyclic compounds, such as cyclobutylamine, cyclohexylamine, aromatic compounds, such as aniline, N, N-dimethylaniline, xylidines, saturated heterocyclic compounds, such as piperidine, pyrrolidine, morpholine, or unsaturated heterocyclic compounds such as pyrrole, pyridine, indole, quinoline, said compounds may be substituted by one or more alkyl group (s) or aryl (s) or alkyl (s) containing unsaturations.

According to a second variant, the organic compound comprises two amine functional groups and does not contain any other functional group.

More particularly, said organic compound comprising two amine functional groups is chosen from aliphatic compounds, such as ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, diaminohexane, tetramethylenediamine, hexamethylenediamine and tetramethylethylenediamine. tetraethylethylenediamine, benzathine, xylylenediamines, diphenylethylenediamine, cyclic or alicyclic compounds, such as 1,2-diaminocyclohexane, aromatic compounds, such as phenylenediamines and their derivatives, 4,4'-diaminobiphenyl, 1, 8-diaminonaphthalene, or heterocyclic compounds such as piperazine, imidazole, pyrimidine, purine, said compounds may be substituted with one or more alkyl group (s) or aryl group (s) or alkyl group (s) containing unsaturations. Preferably, said organic compound is chosen from ethylenediamine, diaminohexane, tetramethylenediamine, hexamethylenediamine, tetramethylethylenediamine and tetraethylethylenediamine.

According to a third variant, the organic compound comprises at least three amine functional groups and does not contain any other functional group. More particularly, said compound is chosen from diethylenetriamine and triethylenetetramine. Among all the organic compounds comprising at least one amine function corresponding to the empirical formula C _x N _y H _z in which 1 <x <20, 1 <y <x, 2 <z <2x + 2 are cited above, it is more preferable to especially ethylenediamine, diaminohexane, tetramethylenediamine, hexamethylenediamine, tetramethylethylenediamine, tetraethylethylenediamine, diethylenetriamine, triethylenetetramine.

In one embodiment of the invention, said organic compound comprises at least one amine function and at least one carboxylic acid function (amino acid). Among the amino acids, said organic compound may be chosen from the following compounds: alanine, arginine, asparagine, pyroglutamic acid, citrulline, gabapentin, glutamine, histidine, isoleucine, isoglutamine, leucine, lysine, norvaline, ornithine, phenylalanine, proline, saccharopine sarcosine, serine, threonine, tryptophan, tyrosine, valine, pyrrolysine, 2-aminoisobutyric acid, ethylene diamine tetraacetic acid (EDTA), according to any of their isomeric forms. When the compound is an amino acid, it is preferably chosen from alanine, arginine, lysine, proline, serine, threonine and EDTA.

Step c Formatting

The paste obtained at the end of the comalaxing step b) is then shaped according to any technique known to those skilled in the art, for example extrusion forming methods, pelletizing, by the method of the invention. drop of oil (dripping) or by granulation at the turntable.

Preferably, the paste is shaped by extrusion in the form of extrudates of diameter generally between 0.5 and 10 mm, preferably 0.8 and 3.2 mm, and very preferably between 1, 0 and 2 , 5 mm. This may advantageously be in the form of cylindrical, trilobed or quadrilobed extrudates. Preferably its shape will be trilobed or quadrilobed.

Very preferably, said comalling step b) and said forming step c) are combined in a single kneading-extrusion step. In this case, the paste obtained after the mixing can be introduced into a piston extruder through a die having the desired diameter, typically between 0.5 and 10 mm.

Step dl Drying the shaped dough According to the invention, the shaped dough undergoes drying d) at a temperature below 250 ° C, preferably between 15 and 240 ° C, more preferably between 30 and 220 ° C, still more preferably between 50 and 200 ° C, and even more preferably between 70 and 180 ° C, for a period of time typically between 10 minutes and 24 hours. Longer durations are not excluded, but do not necessarily improve.

The drying step may be performed by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere or under an atmosphere containing oxygen or under a mixture of inert gas and oxygen. It is advantageously carried out at atmospheric pressure or under reduced pressure. Preferably, this step is carried out at atmospheric pressure and in the presence of air or nitrogen.

Step e) Heat treatment of the dried catalyst (optional)

The catalyst thus dried can then undergo a complementary step of heat or hydrothermal treatment e) at a temperature of between 250 and 1000 ° C. and preferably between 250 and 750 ° C., for a duration of typically between 15 minutes and 10 hours, under an inert atmosphere or under an atmosphere containing oxygen, in the presence of water or not. Longer treatment times are not excluded, but do not require improvement. Several combined cycles of thermal or hydrothermal treatments can be carried out. After this or these treatment (s), the catalyst precursor comprises nickel in oxide form, that is to say in NiO form.

In the case where water is added, the contact with the water vapor can take place at atmospheric pressure or autogenous pressure. The water content is preferably between 150 and 900 grams per kilogram of dry air, and even more preferably between 250 and 650 grams per kilogram of dry air.

Step fl Reduction by a reducing gas (optional!

Prior to the use of the catalyst in the catalytic reactor and the implementation of a hydrogenation process, advantageously at least one reducing treatment step f) is carried out in the presence of a reducing gas after steps d) or e ) to obtain a catalyst comprising nickel at least partially in metallic form.

This treatment makes it possible to activate the said catalyst and to form metal particles, in particular nickel in the zero state. Said reducing treatment can be carried out in situ or ex-situ, that is to say after or before the loading of the catalyst into the hydrogenation reactor.

The reducing gas is preferably hydrogen. The hydrogen can be used pure or as a mixture (for example a hydrogen / nitrogen mixture, hydrogen / argon, hydrogen / methane). In the case where the hydrogen is used as a mixture, all proportions are possible.

Said reducing treatment is carried out at a temperature between 120 and 500 ° C, preferably between 150 and 450 ° C. When the catalyst is not passivated, or undergoes a reducing treatment before passivation, the reducing treatment is carried out at a temperature between 350 and 500 ° C, preferably between 350 and 450 ° C. When the catalyst has been previously passivated, the reducing treatment is generally carried out at a temperature between 120 and 350 ° C, preferably between 150 and 350 ° C. The duration of the reducing treatment is generally between 2 and 40 hours, preferably between 3 and 30 hours. The rise in temperature to the desired reduction temperature is generally slow, for example set between 0.1 and 10 ° C / min, preferably between 0.3 and 7 ° C / min.

The flow rate of hydrogen, expressed in L / hour / g of catalyst is between 0.1 and 100 L / hour / g of catalyst, preferably between 0.5 and 10 L / hour / g of catalyst, still more preferred between 0.7 and 5 L / hour / gram of catalyst.

Step al Passivation (optional ^')

Prior to its implementation in the catalytic reactor, the catalyst according to the invention may optionally undergo a passivation step (step g) with a sulfur or oxygenated compound or with CO ₂ before or after the reducing treatment step f) . This passivation step may be performed ex situ or in situ. The passivation step is carried out by the implementation of methods known to those skilled in the art.

The sulfur passivation step makes it possible to improve the selectivity of the catalysts and to avoid thermal runaways when starting new catalysts ("run away" according to the English terminology). Passivation generally consists in irreversibly poisoning with the sulfur compound the most virulent active sites of the nickel which exist on the new catalyst and thus in attenuating the activity of the catalyst in favor of its selectivity. The passivation step is carried out by the implementation of methods known to those skilled in the art and in particular, for example by the implementation of one of the methods described in patent documents EP0466567, US5153163, FR2676184, WO2004 / 098774, EP0707890. The sulfur compound is, for example, chosen from the following compounds: thiophene, thiophane, alkylmonosulfides such as dimethylsulfide, diethylsulfide, dipropylsulfide and propylmethylsulphide or an organic disulphide of formula HO-R1-SS-R2-OH such as di-thio-di -ethanol of formula HO-C2H4-SS-C2H4-OH (often called DEODS). The sulfur content is generally between 0.1 and 2% by weight of said element relative to the mass of the catalyst.

The passivation step with an oxygenated compound or with CO ₂ is generally carried out after a reducing treatment beforehand at elevated temperature, generally between 350 and 500 ° C., and makes it possible to preserve the metallic phase of the catalyst in the presence of air. . A second reducing treatment at a lower temperature, generally between 120 and 350 ° C., is then generally carried out. The oxygenated compound is generally air or any other stream containing oxygen.

Catalyst characteristics

The catalyst obtained by the preparation process according to the invention is in the form of a composite comprising an oxide matrix having a calcined alumina content greater than or equal to 90% by weight relative to the total weight of said matrix, in which is distributed the active phase comprising nickel, preferably consisting of nickel. The characteristics of the gel which has led to obtaining the alumina contained in said oxide matrix, as well as the textural properties obtained with the active phase, give the catalyst its specific properties.

More particularly, said catalyst comprising an oxide matrix having a calcined alumina content greater than or equal to 90% by weight relative to the total weight of said matrix, and an active phase comprising nickel, preferably consisting of nickel, said active phase not comprising no group VI B metal (Cr, Mo, W), the nickel content being between 1 and 65% by weight of said element relative to the total weight of the catalyst, said active phase being in the form of nickel particles having a diameter of less than or equal to 18 nm, said catalyst comprising a total pore volume measured by mercury porosimetry greater than 0.10 ml / g, a mesoporous volume measured by mercury porosimetry greater than 0.10 ml / g, a volume macroporous measured by mercury porosimetry less than or equal to 0.6 ml / g, a median mesoporous diameter of between 3 and 25 nm, a macroporous median diameter of between 50 and 1500 nm, and an SBET surface area of between 20 and 400 m ² / g. All textural properties (total pore volume, mesoporous volume, macroporous volume, mesoporous median diameter, macroporous median diameter, specific surface area) are measured on the dried catalyst (if the catalyst preparation process does not provide the optional step e) of treatment after drying step d)) or on the catalyst obtained after step e) of heat treatment (if this step is carried out).

The nickel content is between 1 and 65% by weight, preferably between 5 and 55% by weight, preferably between 8 and 40% by weight, and particularly preferably between 10 and 35% by weight, so that more preferably between 12 and 35% by weight, more preferably between 15 and 35% by weight, and more preferably between 18 and 32% by weight of said element relative to the total mass of the catalyst. The Ni content is measured by X-ray fluorescence.

The size of the nickel particles in the catalyst according to the invention, measured in their oxide form, is less than 18 nm, preferably less than 15 nm, more preferably between 0.5 and 12 nm, more preferably between 1 and 8 nm, even more preferably between 1 and 6 nm, and even more preferably between 1, 5 and 5 nm. The active phase of the catalyst does not include a Group VIB metal. It does not include molybdenum or tungsten.

Without wishing to be bound by any theory, it seems that the catalyst obtained by the method of preparation as described above, present when the latter is used in the context of the process for the selective hydrogenation of polyunsaturated compounds or hydrogenation of aromatics according to the invention a good compromise between a high pore volume, a high mesoporous volume and a mesoporous median diameter, a high Ni content, a small size of nickel particles thus making it possible to have hydrogenation performance in terms of activity at least as good as the catalysts known from the state of the prior art.

The catalyst further comprises an oxide matrix having a calcined alumina content greater than or equal to 90% by weight relative to the total weight of said matrix, optionally supplemented with silica and / or phosphorus to a total content of at most 10 % equivalent weight Si0 ₂ and / or P ₂ 0 ₅ , preferably less than 5% by weight, and very preferably less than 2% by weight relative to the total weight of said matrix. Silica and / or phosphorus can be introduced by any technique known to those skilled in the art, during the synthesis of the alumina gel or during the comalaxing.

Even more preferably, the oxide matrix consists of alumina.

Preferably, the alumina present in said matrix is a transition alumina such as gamma, delta, theta, chi, rho or eta alumina, alone or as a mixture. More preferably, the alumina is a gamma, delta or theta transition alumina, alone or as a mixture.

Said catalyst is generally presented in all the forms known to those skilled in the art, for example in the form of beads (generally having a diameter of between 1 and 8 mm), extrudates, tablets, hollow cylinders. Preferably, it consists of extrudates of diameter generally between 0.5 and 10 mm, preferably between 0.8 and 3.2 mm and very preferably between 1.0 and 2.5 mm and of average length. between 0.5 and 20 mm. The term "mean diameter" of the extrudates means the average diameter of the circle circumscribed in the cross-section of these extrusions. The catalyst may advantageously be in the form of cylindrical, multilobed, trilobed or quadrilobed extrudates. Preferably its shape will be trilobed or quadrilobed. The shape of the lobes can be adjusted according to all known methods of the prior art.

The catalyst has a total pore volume of at least 0.10 ml / g, preferably at least 0.30 ml / g, preferably between 0.35 and 1.2 ml / g, more preferentially between 0.4 and 1 mL / g and even more preferably between 0.45 and 0.9 mL / g.

The catalyst advantageously has a macroporous volume less than or equal to 0.6 mL / g, preferably less than or equal to 0.5 mL / g, more preferably less than or equal to 0.4 mL / g, and even more preferably between 0 , 02 and 0.3 mL / g.

The mesoporous volume of the catalyst is at least 0.10 ml / g, preferably at least 0.20 ml / g, preferably between 0.25 ml / g and 0.80 ml / g, more preferably between 0.30 and 0.65 mL / g, and even more preferably between 0.35 and 0.55 mL / g.

The median mesoporous diameter is between 3 nm and 25 nm, and preferably between 6 and 20 nm, and particularly preferably between 8 and 18 nm. The catalyst has a macroporous median diameter of between 50 and 1500 nm, preferably between 80 and 1000 nm, even more preferably between 250 and 800 nm.

The catalyst has a BET specific surface area of between 20 and 400 m ² / g, and more preferably between 30 and 350 m ² / g, and even more preferably between 40 and 250 m ² / g. The specific surface area is measured on the dried catalyst (if the catalyst preparation process does not provide the optional step e) of heat treatment after step d) of drying) or on the catalyst obtained after the treatment step e) thermal (if this step is performed).

Preferably, the catalyst has a low microporosity, very preferably it has no microporosity.

Description of the process for the selective hydrogenation of polyunsaturated compounds

The subject of the present invention is also a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as diolefins and / or acetylenics and / or alkenylaromatiques, also known as styrenics, contained in a polyunsaturated charge. hydrocarbons having a final boiling point less than or equal to 300 ° C, which process is carried out at a temperature of between 0 and 300 ° C, at a pressure of between 0.1 and 10 MPa, at a molar ratio of hydrogen to (polyunsaturated compounds to be hydrogenated) between 0.1 and 10 and at an hourly space velocity of between 0, 1 and 200 h ¹ when the process is carried out in the liquid phase, or at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) between 0.5 and 1000 and at an hourly space velocity between 100 and 40000 h ¹ when the process is carried out in the gaseous phase, in the presence of a catalyst obtained by the process of preparation as described above in the description.

Monounsaturated organic compounds such as, for example, ethylene and propylene, are at the source of the manufacture of polymers, plastics and other value-added chemicals. These compounds are obtained from natural gas, naphtha or gas oil which have been treated by steam cracking or catalytic cracking processes. These processes are operated at high temperature and produce, in addition to the desired monounsaturated compounds, polyunsaturated organic compounds such as acetylene, propadiene and methylacetylene (or propyne), 1-2-butadiene and 1-3 butadiene, vinylacetylene and ethylacetylene, and other polyunsaturated compounds whose boiling point corresponds to the C5 + cut (hydrocarbon compounds having at least 5 carbon atoms), in particular diolefinic or styrenic or indenic compounds. These polyunsaturated compounds are very reactive and lead to spurious reactions in the polymerization units. It is therefore necessary to eliminate them before valuing these cuts.

Selective hydrogenation is the main treatment developed to specifically remove undesired polyunsaturated compounds from these hydrocarbon feeds. It allows the conversion of the polyunsaturated compounds to the corresponding alkenes or aromatics, avoiding their total saturation and thus the formation of the corresponding alkanes or naphthenes. In the case of steam cracking gasolines used as a filler, the selective hydrogenation also makes it possible to selectively hydrogenate alkenyl aromatics to aromatics by avoiding the hydrogenation of the aromatic rings.

The hydrocarbon feedstock treated in the selective hydrogenation process has a final boiling point less than or equal to 300 ° C and contains at least 2 carbon atoms per molecule and comprises at least one polyunsaturated compound. The term "polyunsaturated compounds" means compounds comprising at least one acetylenic function and / or at least one diene function and / or at least one alkenylaromatic function.

More particularly, the filler is selected from the group consisting of a C2 steam cracking cut, a C2-C3 steam cracking cut, a steam cracking C3 cut, a steam cracking C4 cut, a steam cracking C5 cut and a still called steam cracking gasoline. pyrolysis gasoline or C5 + cut.

The steam cracking section C2, advantageously used for carrying out the selective hydrogenation process according to the invention, has for example the following composition: between 40 and 95% by weight of ethylene, of the order of 0.1 to 5% by weight of acetylene, the remainder being essentially ethane and methane. In certain steam cracking sections, between 0.1 and 1% by weight of C 3 compounds may also be present.

The C3 steam-cracking cut, advantageously used for carrying out the selective hydrogenation process according to the invention, has, for example, the following average composition: of the order of 90% by weight of propylene, of the order of 1 to 8% by weight of propadiene and methylacetylene, the remainder being essentially propane. In some C3 cuts, between 0.1 and 2% by weight of C 2 compounds and C 4 compounds may also be present. A C2 - C3 cut can also be advantageously used for the implementation of the selective hydrogenation process according to the invention. It has for example the following composition: of the order of 0.1 to 5% by weight of acetylene, of the order of 0.1 to 3% by weight of propadiene and methylacetylene, of the order of 30% by weight ethylene, of the order of 5% by weight of propylene, the remainder being essentially methane, ethane and propane. This filler may also contain between 0.1 and 2% by weight of C4 compounds.

The C4 steam-cracking cut, advantageously used for the implementation of the selective hydrogenation process according to the invention, has for example the following average mass composition: 1% weight of butane, 46.5% weight of butene, 51% by weight butadiene, 1.3% by weight of vinylacetylene and 0.2% by weight of butyne. In some C4 cuts, between 0.1 and 2% by weight of C3 compounds and C5 compounds may also be present.

The C5 steam-cracking cut, advantageously used for carrying out the selective hydrogenation process according to the invention, has, for example, the following composition: 21% by weight of pentanes, 45% by weight of pentenes and 34% by weight of pentadienes.

The steam cracking gasoline or pyrolysis gasoline, advantageously used for carrying out the selective hydrogenation process according to the invention, corresponds to a hydrocarbon fraction whose boiling point is generally between 0 and 300 ° C., preferably between 10 and 250 ° C. The polyunsaturated hydrocarbons to be hydrogenated present in said steam cracking gasoline are, in particular, diolefinic compounds (butadiene, isoprene, cyclopentadiene, etc.), styrenic compounds (styrene, alpha-methylstyrene, etc.) and indene compounds (indene). ). Steam cracking gasoline generally comprises the C5-C12 cut with traces of C3, C4, C13, C14, C15 (for example between 0.1 and 3% by weight for each of these cuts). For example, a charge formed of pyrolysis gasoline generally has the following composition: 5 to 30% by weight of saturated compounds (paraffins and naphthenes), 40 to 80% by weight of aromatic compounds, 5 to 20% by weight of mono-olefins, 5 to 40% by weight of diolefins, 1 to 20% by weight of alkenylaromatic compounds, all the compounds forming 100%. It also contains from 0 to 1000 ppm by weight of sulfur, preferably from 0 to 500 ppm by weight of sulfur.

Preferably, the polyunsaturated hydrocarbon feedstock treated according to the selective hydrogenation process according to the invention is a C2 steam cracking cut, or a C2-C3 steam cracking cut, or a steam cracking gasoline. The selective hydrogenation process according to the invention aims at eliminating said polyunsaturated hydrocarbons present in said feedstock to be hydrogenated without hydrogenating the monounsaturated hydrocarbons. For example, when said feed is a C2 cut, the selective hydrogenation process aims to selectively hydrogenate acetylene. When said feedstock is a C3 cut, the selective hydrogenation process aims to selectively hydrogenate propadiene and methylacetylene. In the case of a C4 cut, it is intended to remove butadiene, vinylacetylene (VAC) and butyne, in the case of a C5 cut, it is intended to eliminate pentadienes. When said feed is a steam cracking gasoline, the selective hydrogenation process aims to selectively hydrogenate said polyunsaturated hydrocarbons present in said feed to be treated so that the diolefinic compounds are partially hydrogenated to mono-olefins and that the styrenic and indene compounds are partially hydrogenated to corresponding aromatic compounds by avoiding the hydrogenation of aromatic rings.

The technological implementation of the selective hydrogenation process is carried out, for example, by injection, in ascending or descending current, of the polyunsaturated hydrocarbon feedstock and hydrogen in at least one fixed bed reactor. Said reactor may be of the isothermal or adiabatic type. An adiabatic reactor is preferred. The polyunsaturated hydrocarbon feed may advantageously be diluted by one or more re-injection of the effluent from said reactor, where the selective hydrogenation reaction occurs, at various points in the reactor, located between the inlet and the outlet. reactor outlet to limit the temperature gradient in the reactor. The technological implementation of the selective hydrogenation process according to the invention may also be advantageously carried out by implanting at least one of said supported catalyst in a reactive distillation column or in reactor-exchangers or in a slurry-type reactor. . The flow of hydrogen can be introduced at the same time as the feedstock to be hydrogenated and / or at one or more different points of the reactor.

The selective hydrogenation of the steam-cracking cuts C2, C2-C3, C3, C4, C5 and C5 + can be carried out in the gaseous phase or in the liquid phase, preferably in the liquid phase for the C3, C4, C5 and C5 + cuts and in the phase gaseous for C2 and C2-C3 cuts. A reaction in the liquid phase makes it possible to lower the energy cost and to increase the catalyst cycle time.

In general, the selective hydrogenation of a hydrocarbon feed containing polyunsaturated compounds containing at least 2 carbon atoms per molecule and having a final boiling point of less than or equal to 300 ° C. is carried out at a temperature of between 0 and 300 ° C., at a pressure of between 0.1 and 10 MPa, at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) ) between 0, 1 and 10 and at an hourly space velocity VVH (defined as the ratio of the volume flow rate of charge to the volume of the catalyst) of between 0, 1 and 200 h ¹ for a process carried out in the liquid phase, or a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) of between 0.5 and 1000 and at a hourly space velocity VVH of between 100 and 40,000 h ¹ for a process carried out in the gas phase.

In one embodiment according to the invention, when a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline containing polyunsaturated compounds, the molar ratio (hydrogen) / (polyunsaturated compounds to be hydrogenated) is generally understood. between 0.5 and 10, preferably between 0.7 and 5.0 and even more preferably between 1.0 and 2.0, the temperature is between 0 and 200 ° C, preferably between 20 and 200 ° C and even more preferably between 30 and 180 ° C, the hourly volume velocity (VVH) is generally between 0.5 and 100 h ¹ , preferably between 1 and 50 h ¹ and the pressure is generally between 0, 3 and 8.0 MPa, preferably between 1.0 and 7.0 MPa and even more preferably between 1.5 and 4.0 MPa.

More preferably, a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) is between 0.7 and 5.0, the temperature is between 20 and 200 ° C, the hourly volume velocity (VVH) is generally between 1 and 50 h ¹ and the pressure is between 1.0 and 7.0 MPa.

Even more preferentially, a selective hydrogenation process is carried out in which the feedstock is a steam cracking gasoline comprising polyunsaturated compounds, the molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) is between 1.0 and 2.0, the temperature is between 30 and 180 ° C, the hourly volume velocity (VVH) is generally between 1 and 50 h ¹ and the pressure is between 1, 5 and 4.0 MPa.

The hydrogen flow rate is adjusted in order to dispose of it in sufficient quantity to theoretically hydrogenate all of the polyunsaturated compounds and to maintain an excess of hydrogen at the outlet of the reactor.

In another embodiment according to the invention, when a selective hydrogenation process is carried out in which the feedstock is a C2 steam cracking cut and / or a C2-C3 steam cracking section comprising polyunsaturated compounds, the molar ratio (hydrogen) / (polyunsaturated compounds to be hydrogenated) is generally between 0.5 and 1000, preferably between 0.7 and 800, the temperature is between 0 and and 300 ° C, preferably between 15 and 280 ° C, the hourly volume velocity (VVH) is generally between 100 and 40000 h ¹ , preferably between 500 and 30000 h ¹ and the pressure is generally between 0.1 and 6.0 MPa, preferably between 0.2 and 5.0 MPa.

Description of aromatics

The subject of the present invention is also a process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point of less than or equal to 650 ° C., generally between 20 and 650 ° C. and preferably between 20 and 450 ° C. Said hydrocarbon feedstock containing at least one aromatic or polyaromatic compound may be chosen from the following petroleum or petrochemical cuts: catalytic reforming reformate, kerosene, light gas oil, heavy gas oil, cracking distillates, such as FCC recycling oil, coker unit diesel, hydrocracking distillates.

The content of aromatic or polyaromatic compounds contained in the hydrocarbon feedstock treated in the hydrogenation process according to the invention is generally between 0.1 and 80% by weight, preferably between 1 and 50% by weight, and particularly preferably between 2 and 35% by weight, the percentage being based on the total weight of the hydrocarbon feed. The aromatic compounds present in said hydrocarbon feedstock are, for example, benzene or alkylaromatics such as toluene, ethylbenzene, o-xylene, m-xylene or p-xylene, or else aromatics having several aromatic (polyaromatic) rings such as naphthalene.

The sulfur or chlorine content of the feedstock is generally less than 5000 ppm by weight of sulfur or chlorine, preferably less than 100 ppm by weight, and particularly preferably less than 10 ppm by weight.

The technological implementation of the process for the hydrogenation of aromatic or polyaromatic compounds is for example carried out by injection, in ascending or descending current, of the hydrocarbon feedstock and hydrogen in at least one fixed bed reactor. Said reactor may be of the isothermal or adiabatic type. An adiabatic reactor is preferred. The hydrocarbon feedstock can advantageously be diluted by one or more re-injection (s) of the effluent, from said reactor where the aromatic hydrogenation reaction occurs, at various points of the reactor, situated between the inlet and the outlet of the reactor in order to limit the gradient of temperature in the reactor. The technological implementation of the process for the hydrogenation of aromatics according to the invention can also be advantageously carried out by implanting at least one of said supported catalyst in a reactive distillation column or in reactor-exchangers or in a reactor of the following type slurry. The flow of hydrogen can be introduced at the same time as the feedstock to be hydrogenated and / or at one or more different points of the reactor.

The hydrogenation of the aromatic or polyaromatic compounds can be carried out in the gas phase or in the liquid phase, preferably in the liquid phase. In general, the hydrogenation of the aromatic or polyaromatic compounds is carried out at a temperature of between 30 and 350 ° C., preferably between 50 and 325 ° C., at a pressure of between 0.1 and 20 MPa, preferably between 0.5 and 10 MPa, at a hydrogen / (aromatic compounds to be hydrogenated) molar ratio between 0.1 and 10 and at a hourly volume velocity VVH between 0.05 and 50 h ¹ , preferably between 0.1 and 10 h ¹ of a hydrocarbon feedstock containing aromatic or polyaromatic compounds and having a final boiling point less than or equal to 650 ° C, generally between 20 and 650 ° C, and preferably between 20 and 450 ° C .

The hydrogen flow rate is adjusted in order to dispose of it in sufficient quantity to theoretically hydrogenate all the aromatic compounds and to maintain an excess of hydrogen at the outlet of the reactor.

The conversion of the aromatic or polyaromatic compounds is generally greater than 20 mol%, preferably greater than 40 mol%, more preferably greater than 80 mol%, and particularly preferably greater than 90 mol% of the aromatic compounds. or polyaromatic content contained in the hydrocarbon feedstock. The conversion is calculated by dividing the difference between the total moles of the aromatic or polyaromatic compounds in the hydrocarbon feedstock and the product by the total moles of the aromatic or polyaromatic compounds in the hydrocarbon feedstock.

According to a particular variant of the process according to the invention, a process is carried out for the hydrogenation of benzene from a hydrocarbon feedstock, such as the reformate resulting from a catalytic reforming unit. The benzene content in said hydrocarbon feedstock is generally between 0.1 and 40% by weight, preferably between 0.5 and 35% by weight, and particularly preferably between 2 and 30% by weight, the percentage by weight being based on the total weight of the hydrocarbon feed.

The sulfur or chlorine content of the feedstock is generally less than 10 ppm by weight of sulfur or chlorine respectively, and preferably less than 2 ppm by weight.

The hydrogenation of the benzene contained in the hydrocarbon feed can be carried out in the gas phase or in the liquid phase, preferably in the liquid phase. When carried out in the liquid phase, a solvent may be present, such as cyclohexane, heptane or octane. In general, the hydrogenation of benzene is carried out at a temperature of between 30 and 250 ° C., preferably between 50 and 200 ° C., and more preferably between 80 and 180 ° C., at a pressure comprised between between 0.1 and 10 MPa, preferably between 0.5 and 4 MPa, at a hydrogen / (benzene) molar ratio between 0.1 and 10 and at a hourly volume velocity VVH between 0.05 and 50 h ¹ , preferably between 0.5 and 10 h ¹ .

The conversion of benzene is generally greater than 50 mol%, preferably greater than 80 mol%, more preferably greater than 90 mol% and particularly preferably greater than 98 mol%.

The invention is illustrated by the following examples.

Example 1 Preparation of an aqueous solution of Ni precursors

The aqueous solution of Ni precursors (solution S) used for the preparation of catalysts B and C is prepared by dissolving 46.1 g of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O, supplier Strem Chemicals®) in a volume of 13 mL of distilled water. Solution S is obtained whose NiO concentration is 20.1% by weight (relative to the mass of the solution).

Example 2: Preparation of a calcined aluminous porous oxide (according to embodiment 2)

The synthesis of alumina A is carried out in a laboratory reactor with a capacity of about 7000 ml. The synthesis is carried out at 70 ° C with stirring in six steps, named below (a1 ') to a6'). It is sought to prepare 5 L of solution at a concentration of 27 g / L of alumina in the final suspension (obtained at the end of step a3 ') and with a contribution rate of the first step (a1') at 2.1% of the total alumina.

a1 ') Dissolving: 70 ml of aluminum sulphate Al ₂ (SO ₄ ) _{3 are} introduced in one go into the reactor containing a foot of water of 1679 ml. The evolution of the pH, which remains between 2.5 and 3, is followed for 10 minutes. This step contributes to the introduction of 2.1% of alumina relative to the total mass of alumina formed at the end of the synthesis of the gel. The solution is stirred for a period of 10 minutes.

A2 ') pH adjustment: About 70 ml of NaAlOO sodium aluminate are gradually added. The goal is to reach a pH between 7 and 10 in a period of 5 to 15 minutes.

a3 ') Coprecipitation: In the suspension obtained at the end of step a2') is added in 30 minutes,

1020 ml of aluminum sulfate AI ₂ (SO ₄ ) ₃ , ie a flow rate of 34 ml / min,

1020 mL of NaAlOO sodium aluminate, a flow rate of 34 mL / min,

- 1150 mL of distilled water, a flow rate of 38.3 mL / min.

The pH is between 8.7 and 9.9.

a4 ') Filtration: The suspension obtained at the end of step a3') is filtered by displacement on a sintered Buchner tool P4 and washed several times with distilled water. An alumina gel is obtained.

a5 ') Drying: The alumina gel obtained at the end of step a4') is dried in an oven for 16 hours at 200 ° C.

a6 ') Heat treatment: The powder obtained at the end of step a5') is then calcined under a flow of air of 1 L / h / g of alumina gel at 750 ° C. for 2 hours to obtain the transition from boehmite to alumina. Alumina A is then obtained.

Example 3 (Comparative) Preparation of a catalyst B by impregnation of nickel nitrate without additive

Catalyst B is prepared by dry impregnation of alumina A described in Example 2 with solution S of Ni precursors.

The synthesis of alumina A is carried out by following the six steps, steps aT) to a6 '), of Example 2 described above. The operating conditions are strictly identical. However, a shaping step of the dried alumina gel from step a5 ') is inserted between steps a5') and a6 '): The shaping of this powder is carried out on a Brabender type kneader. with an acid content of 1% (total acid level, expressed relative to dry alumina), a neutralization rate of 20% and acid and basic fire losses of 62% and 64% respectively. The extrusion is then carried out on a piston extruder through a 2.1 mm diameter die. After extrusion, the extrusions are dried for 16 hours at 80 ° C. At the end of step a6 ') of calcination, extrudates of alumina A are obtained.

The solution S prepared in Example 1 is impregnated dry with 10 g of alumina A. The solid thus obtained is then dried in an oven for 16 hours at 120 ° C. and then calcined under a flow of air of 1 L / h / g catalyst at 450 ° C for 2 hours.

The calcined catalyst B thus prepared contains 23.2% by weight of the nickel element relative to the total weight of the catalyst supported on alumina and it has crystallites of nickel oxide whose average diameter (determined by X-ray diffraction at from the width of the diffraction line at the angle 2theta = 43 °) is 15.6 nm. The other structural characteristics of catalyst B are listed in Table 1 below.

Example 4 (Comparative) Preparation of a catalyst C by comalaxaae without additive

Catalyst C is prepared from alumina A and Ni precursor solution S, prepared above, according to the following four steps:

Comalaxing: A "Brabender" mixer is used with a bowl of 80 mL and a mixing speed of 30 rpm. Alumina powder A is placed in the bowl of the kneader. Then solution S of Ni precursors is added gradually to the syringe for about 10 minutes at 15 rpm while heating to evacuate the water. After obtaining a paste, the kneading is maintained for 15 minutes at 50 rpm.

Extrusion: The paste thus obtained is introduced into a piston extruder and is extruded through a 2.1 mm diameter die.

Drying: The extrudates thus obtained are then dried in an oven at 80 ° C. for 16 hours. A dried catalyst is obtained.

Heat treatment: The dried catalyst is then calcined in a tubular furnace, under a flow of air of 1 L / h / g of catalyst, at 450 ° C for 2 hours (ramp temperature rise of 5 ° C / min).

The calcined catalyst C, which contains 24.3% by weight of the nickel element relative to the total weight of the comalaxed catalyst, is then obtained and has nickel oxide crystallites with an average diameter of 9.5 nm. The other structural characteristics of catalyst C are listed in Table 1 below. nickel nitrate and propanedioic acid (malonic acid)

Catalyst D is prepared by dry co-impregnation of nickel nitrate and malonic acid on alumina A using a molar ratio {malonic acid / nickel} equal to 0.6. For this purpose, an aqueous solution S 'is prepared by dissolving 89.0 g of nickel nitrate Ni (N0 ₃ ) ₂ .6H ₂ O (supplier Strem Chemicals®) and 19.1 g of malonic acid (CAS 141- 82-2, Fluka® supplier) in 20 mL of demineralized water. This solution S 'is then impregnated dry on 10 g of alumina A previously shaped in the form of extrudates as described above in Example 3. The solid thus obtained is then dried in an oven for 16 hours at 120.degree. ° C, then calcined under an air flow of 1 L / h / g of catalyst at 450 ° C for 2 hours.

The calcined catalyst D thus prepared contains 22.9% by weight of the nickel element relative to the total weight of the catalyst supported on alumina and has nickel oxide crystallites with an average diameter of 4.8 nm. The other structural characteristics of the catalyst D are listed in Table 1 below.

Example 6 a catalyst E in the presence of prc acid

Catalyst E is prepared from alumina A and solution S 'containing the precursor of Ni and propanedioic acid, prepared above, according to the following four steps:

Comalaxing: A "Brabender" mixer is used with a bowl of 80 mL and a mixing speed of 30 rpm. Alumina powder A is placed in the bowl of the kneader. Then the precursor solution S 'of Ni and propanedioic acid is added gradually to the syringe for about 10 minutes at 15 rpm while heating to evacuate the water. After obtaining a paste, the kneading is maintained for 15 minutes at 50 rpm.

Heat treatment: The dried catalyst is then calcined in a tubular furnace, under a flow of air of 1 L / h / g of catalyst, at 450 ° C for 2 hours (ramp temperature rise of 5 ° C / min). The calcined catalyst E which contains TI, 7% by weight of the nickel element relative to the total weight of the comalaxed catalyst is then obtained and has crystallites of nickel oxide whose average diameter is 4.2 nm. The other structural characteristics of catalyst E are listed in Table 1 below.

Table 1: Properties of catalysts B, C, D (not in accordance with the method of

preparation according to the invention), and E (compliant)

Example 7 Evaluation of the Catalytic Properties of Catalysts B. C, D and E in Selective Hydrogenation of a Mixture Containing Styrene and Isoprene

Catalysts B, C, D and E described in the examples above are tested for the selective hydrogenation reaction of a mixture containing styrene and isoprene.

The composition of the filler to be selectively hydrogenated is as follows: 8% by weight styrene (supplier Sigma Aldrich®, purity 99%), 8% by weight isoprene (supplier Sigma Aldrich®, purity 99%), 84% by weight n-heptane (solvent ) (VWR® supplier, purity> 99% chromanorm HPLC). This feed also contains sulfur compounds in very low content: 10 ppm wt of sulfur introduced in the form of pentanethiol (supplier Fluka®, purity> 97%) and 100 ppm wt of sulfur introduced in the form of thiophene (Merck® supplier, purity 99 %). This composition corresponds to the initial composition of the reaction mixture. This mixture of model molecules is representative of a pyrolysis species.

The selective hydrogenation reaction is carried out in a 500 ml autoclave made of stainless steel, equipped with magnetic stirring mechanical stirring and capable of operating at a maximum pressure of 100 bar (10 MPa) and temperatures of between 5 ° C. and 5 ° C. 200 ° C.

Prior to its introduction into the autoclave, a quantity of 3 mL of catalyst is reduced ex situ under a flow of hydrogen of 1 L / h / g of catalyst, at 400 ° C. for 16 hours (temperature rise ramp of 1 ° C / min), then it is transferred to the autoclave, protected from the air. After addition of 214 mL of n-heptane (supplier VWR®, purity> 99% chromanorm HPLC), the autoclave is closed, purged, then pressurized under 35 bar (3.5 MPa) of hydrogen, and brought to temperature. test equal to 30 ° C. At time t = 0, about 30 g of a mixture containing styrene, isoprene, n-heptane, pentanethiol and thiophene are introduced into the autoclave. The reaction mixture then has the composition described above and stirring is started at 1600 rpm. The pressure is kept constant at 35 bar (3.5 MPa) in the autoclave using a reservoir bottle located upstream of the reactor.

The progress of the reaction is monitored by taking samples of the reaction medium at regular time intervals: the styrene is hydrogenated to ethylbenzene, without hydrogenation of the aromatic ring, and the isoprene is hydrogenated to methyl-butenes. If the reaction is prolonged longer than necessary, the methyl-butenes are in turn hydrogenated to isopentane. Hydrogen consumption is also monitored during time by reducing the pressure in a reservoir bottle located upstream of the reactor. The catalytic activity is expressed in moles of H ₂ consumed per minute and per gram of Ni.

The catalytic activities measured for catalysts B, C, D and E are reported in Table 2 below. They are related to the catalytic activity measured for catalyst B (A _H YDI) ·

Table 2: Comparison of the performances in selective hydrogenation of a mixture containing styrene and isoprene (A _H YDI) and hydrogenation of toluene (A _H YD2) This shows the improved performance of the catalyst E prepared according to the invention and in particular the impact of the use of a step of mixing the active phase in the presence of an organic additive rather than an impregnation step. Indeed, the catalyst D, although having NiO crystallites of size substantially equal to those of the catalyst E, has poorer catalytic performance. In addition, the addition of a specific organic compound during the kneading step makes it possible to obtain improved performances (relative to the activity of the non-conforming catalyst C being prepared by a process without the addition of malonic acid during of the mixing step). The high content of nickel element and the very small Ni particles present on the catalyst E prepared according to the invention are also noted by mixing the active phase in the presence of an organic additive. Example 8 Evaluation of the Catalytic Properties of Catalysts B, C, D and E in Hydrogenation of Toluene

Catalysts B, C, D and E described in the above examples are also tested against the hydrogenation reaction of toluene.

The selective hydrogenation reaction is carried out in the same autoclave as that described in Example 6.

Prior to its introduction into the autoclave, a quantity of 2 mL of catalyst is reduced ex situ under a flow of hydrogen of 1 L / h / g of catalyst, at 400 ° C. for 16 hours (temperature rise ramp of 1 ° C / min), then it is transferred to the autoclave, protected from the air. After addition of 216 ml of n-heptane (supplier VWR®, purity> 99% chromanorm HPLC), the autoclave is closed, purged and then pressurized under 35 bar (3.5 MPa) of hydrogen, and brought to temperature. test equal to 80 ° C. At time t = 0, about 26 g of toluene (supplier SDS®, purity> 99.8%) are introduced into the autoclave (the initial composition of the reaction mixture is then toluene 6% w / n-heptane 94% wt) and stirring is started at 1600 rpm. The pressure is kept constant at 35 bar (3.5 MPa) in the autoclave using a reservoir bottle located upstream of the reactor.

The progress of the reaction is monitored by taking samples of the reaction medium at regular time intervals: toluene is completely hydrogenated to methylcyclohexane. Hydrogen consumption is also monitored over time by the pressure decrease in a reservoir bottle located upstream of the reactor. The catalytic activity is expressed in moles of H ₂ consumed per minute and per gram of Ni.

The catalytic activities measured for catalysts B, C, D and E are reported in Table 2 above. They are related to the catalytic activity measured for catalyst B (AHYD2) ·

This shows the improved performance of the catalyst E prepared according to the invention and in particular the impact of the use of a step of mixing the active phase in the presence of an organic additive rather than an impregnation step. Indeed, the catalyst D, although having NiO crystallites of size substantially equal to those of the catalyst E, has poorer catalytic performance. In addition, the addition of a specific organic compound during the kneading step makes it possible to obtain improved performances (relative to the activity of the non-conforming catalyst C being prepared by a process without adding malonic acid during the kneading step). The high content of nickel element and the very small Ni particles present on the catalyst E prepared according to the invention are also noted by mixing the active phase in the presence of an organic additive.

Claims

A process for preparing a catalyst comprising an oxide matrix having a calcined alumina content greater than or equal to 90% by weight relative to the total weight of said matrix, and an active phase comprising nickel, said active phase not comprising any group VIB metal, the nickel content being between 1 and 65% by weight of said element relative to the total weight of the catalyst, said active phase being in the form of nickel particles having a diameter of less than or equal to 18 nm, said catalyst comprising a total pore volume measured by mercury porosimetry greater than 0.10 ml / g, a mesoporous volume measured by mercury porosimetry greater than 0.10 ml / g, a macroporous volume measured by mercury porosimetry less than or equal to 0.6 ml / g, a median mesoporous diameter of between 3 and 25 nm, a macroporous median diameter of between 50 and 1500 nm, and a SBET specific surface area of between 20 and 20 nm. t 400 m ² / g, which process comprises the following steps:

a) a calcined aluminous porous oxide is prepared;

c) shaping the paste obtained in step b);

2. Method according to claim 1, characterized in that said organic compound comprises at least one carboxylic acid function.

3. Method according to claim 2, characterized in that said organic compound is selected from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids.

4. Method according to any one of claims 1 to 3, characterized in that said organic compound comprises at least one alcohol function.

The method of claim 4, wherein said organic compound is selected from:

organic compounds comprising a single alcohol function;

organic compounds comprising two alcohol functions;

organic compounds chosen from diethylene glycol, triethylene glycol, tetraethylene glycol, or a polyethylene glycol having the formula H (OC ₂ H ₄ ) _n OH with n greater than 4 and having an average molecular weight of less than 20000 g / mol; monosaccharides of formula C _n (H ₂ 0) _p with n between 3 and 12;

disaccharides, trisaccharides, or monosaccharide derivatives.

6. Method according to any one of claims 1 to 5, characterized in that said organic compound comprises at least one ester function.

The method of claim 6, wherein said organic compound is selected from:

linear or cyclic or cyclic unsaturated esters of carboxylic acid;

organic compounds comprising at least two carboxylic acid ester functions;

cyclic or linear esters of carbonic acid;

linear diesters of carbonic acid.

8. Method according to any one of claims 1 to 7, characterized in that said organic compound comprises at least one amide function.

The process of claim 8, wherein said organic compound is selected from:

acyclic amides comprising one or two amide functions;

cyclic amides or lactams;

The process according to any one of claims 1 to 9, wherein said organic compound comprises at least one amine function having the empirical formula C _x N _y H _z wherein x is from 1 to 20, y = 1- x and z = 2- (2x + 2).

11. A process according to any one of claims 1 to 10, wherein said calcined aluminous porous oxide according to step a) is obtained by the following steps: a1) a first precipitation step, in an aqueous reaction medium, from at least one basic precursor selected from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid and nitric acid, in which at least one of the basic or acidic precursors comprises aluminum, the relative flow of acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain a degree of progress of the first stage between 5 and 13%, the rate of progress being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said first precipitation step relative to the total amount of alumina formed at the end of step a3) of the process of preparation, said step operating at a temperature between 20 and 90 ° C and for a period of between 2 minutes and 30 minutes;

a2) a step of heating the suspension at a temperature between 40 and 90 ° C for a period of between 7 minutes and 45 minutes, a3) a second step of precipitating the suspension obtained at the end of the heating step a2) by adding to the suspension at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, acid hydrochloric acid and nitric acid, wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10, And the flow rate of the aluminum-containing acidic and basic precursor (s) is adjusted so as to obtain a progress rate of the second step of between 87 and 95%, the rate of progress being defined as the proportion of alumina formed in Al ₂ 0 ₃ equivalent during said second precipitation step relative to the total amount of alumina formed at the end of step a3) of the preparation process, said step operating at a temperature between 40 and 90 ° C and for a period of time between 2 minutes and 50 minutes;

a5) a step of drying said alumina gel obtained in step a4) to obtain a powder;

The process according to any one of claims 1 to 10, wherein said calcined aluminous porous oxide according to step a) is obtained by the following steps:

a2 ') a step of adjusting the pH by adding to the suspension obtained in step a1') at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide, to a temperature between 20 and 90 ° C, and at a pH between 7 and 10, for a period of between 5 and 30 minutes,

a5 ') a step of drying said alumina gel obtained in step a4') to obtain a powder,

a1 ") at least a first step of precipitating alumina, in aqueous reaction medium, of at least one basic precursor chosen from sodium aluminate, potassium aluminate, aqueous ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, in wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursors containing aluminum are set so as to obtain an advancement rate of said first stage of between 40 and 100%, the advancement rate being defined as the proportion of alumina formed in equivalent AI203 during said first precipitation step relative to the total amount of alumina formed at the end of step c) of the process of preparation, said first precipitation step operating at a temperature between 10 and 50 ° C, and for a time between 2 minutes and 30 minutes;

14. Process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as diolefins and / or acetylenes and / or alkenylaromates, contained in a hydrocarbon feed having a lower final boiling point or equal to 300 ° C., which process is carried out at a temperature of between 0 and 300 ° C., at a pressure of between 0.1 and 10 MPa, at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) of between 0, 1 and 10 and at a hourly space velocity of between 0.1 and 200 h ¹ when the process is carried out in the liquid phase, or at a molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) of between 0.5 and 1000 and at a temperature of hourly volume velocity between 100 and 40000 h ¹ when the process is carried out in the gaseous phase, in the presence of a catalyst obtained according to any one of claims 1 to 13.

15. A process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point of less than or equal to 650 ° C., said process being carried out in the gas phase or in the liquid phase, a temperature between 30 and 350 ° C, at a pressure of between 0.1 and 20 MPa, at a molar ratio of hydrogen / (aromatic compounds to be hydrogenated) between 0.1 and 10 and at a hourly volume velocity VVH of between 0.05 and 50 h ¹ , in the presence of a catalyst obtained according to any one of Claims 1 to 13.